Maintenance of cars: Maintenance of mechanisms and transmission units. Maintenance and current repair of transmission units Repair of transmission units

Inept driving a car, first of all, is reflected in the state of the transmission. Sharp jerks, overloading of mechanisms during operation, poor lubrication lead to breakdowns and malfunctions that disable the car for a long time. The vehicle transmission includes: clutch; Transmission; cardan shaft; differential; main gear; hinges of equal angular velocities.

Signs of a malfunction of the transmission mechanisms are: incomplete disengagement of the clutch, difficult engagement or spontaneous disengagement of gears in the box, jerks when the engine load changes, beating and vibration of shafts cardan transmission.

All malfunctions must be promptly eliminated and prevented by thoroughly performing maintenance.

Carrying out TO-1, check and, if necessary, adjust the amount of free travel of the clutch pedal; check the oil level in the gearbox housings, transfer case and driving axles, tighten the nuts of the gearbox mounting bolts.

During TO-2, in addition to the work performed during TO-1, the tightness of the connection of the gearbox housings is checked, the condition thrust bearings cardan gear, backlash of bearings of the shaft of the leading bevel gear of the main gear, condition and adjustment of bearings rear wheels... In addition, they change the lubricant in the crankcases of the transmission units, if it coincides with the corresponding period according to the lubrication schedule.

In the clutch mechanism, malfunctions may occur: incomplete engagement (the clutch slips) or incomplete disengagement (the clutch leads), as well as a sharp engagement of the clutch. EO: Check the action of the clutch mechanism by starting the vehicle and shifting gears while driving. TO-1: Check free run pedal (and, if necessary, adjust it), the condition and fastening of the retractor spring. Lubricate (according to the lubrication schedule) the clutch pedal shaft and the clutch release bearing. Check the clutch function. TO-2: Check the full and free travel of the clutch pedal and the action of the return spring, the operation of the clutch drive and, if necessary, adjust the clutch and drive. Clutch repair consists of removing it from the vehicle, checking the condition of the parts, replacing worn parts and installing the clutch on the vehicle. The need to remove the clutch from the car for repair arises when it is not possible to restore its normal operation by adjusting the drive.

The main signs of gearbox malfunctions are noise during operation, difficult gear shifting, spontaneous gear disengagement, oil leakage, simultaneous engagement of two gears and difficult gear shifting. EO: Check the operation of the gearbox while driving. TO-1: Check and, if necessary, tighten the gearbox mount, if necessary add oil to the level. Check transmission function after service. TO-2: Carry out an in-depth inspection of the gearbox. Check and, if necessary, tighten the gearbox mount to the clutch housing and gearbox housing cover. Check and, if necessary, tighten the fastening of the bearing cap of the driven and intermediate shaft... Top up or replace gearbox oil (per lubrication schedule).

In the cardan drive, wear of bearings, cardan crosspieces and sliding spline coupling, bending or twisting are possible cardan shaft... In the main gear and differential the following is possible: wear or breakage of the gear teeth; wear of the differential cross and bearings; wear or damage to oil seals; oil leakage in the crankcase joints rear axle... A sign of a driveline malfunction are jerks and shocks when starting off or shifting gears on the move. Shaft runout during rotation indicates that the shaft is bent. EO: Check the operation of the cardan and main gears when the car is moving. TO-1: Check and, if necessary, fix the flanges of cardan joints and axle shafts. Secure final drive housing covers. Check the oil level in the drive axle housing and top up if necessary. Lubricate universal joints and suspension bearing (according to the lubrication schedule). TO-2: Check for play in the cardan joints. Fasten the flanges of the axle shafts, cardan shafts and the support bearing to the frame. Check the tightness of the drive axle connections. Check the oil level or replace the oil in the drive axle housing. Lubricate the driveline splined coupling (according to the lubrication schedule). Driveshaft malfunctions are eliminated by restoring or replacing worn parts. The bent shaft must be corrected. Small clearances in the bearings and between the teeth of the final drive are eliminated by adjustments that must be made by experienced mechanics. If the parts of the final drive and differential are heavily worn, they must be replaced.

9. Maintenance transmission and chassis of the car

Mismanagement of the car, first of all, is reflected in the state of the transmission. Sharp jerks, overloading of mechanisms during operation, poor lubrication lead to breakdowns and malfunctions that permanently disable the car. Clutch malfunctions. Malfunctions can occur in the clutch mechanism: incomplete engagement (the clutch slips) or incomplete disengagement (the clutch leads), as well as abrupt engagement of the clutch. A faulty clutch makes it difficult to drive and thus affects driving safety.

When the clutch slips, the torque from the engine shaft is not fully transferred to the drive wheels (especially when the vehicle is moving uphill with a load). With an increase in the speed of the engine crankshaft when the clutch pedal is released, the car does not move at all, or its speed increases very slowly; sometimes the car jerks and the smell of burnt friction linings and driven discs is felt in the cab. Reasons for slipping clutch:

the absence of a gap between the clutch bearing and the engaging levers when the clutch pedal is released, as a result of which the driving disc is not fully pressed against the driven one; to eliminate this malfunction, it is necessary to check and adjust the free travel of the clutch pedal;

oiling of the clutch discs; this malfunction occurs when the bearing of the clutch release clutch is excessively lubricated when grease flows through the rear main bearing crankshaft; in this case, the friction force decreases sharply and the discs slip. To eliminate this malfunction, the clutch must be disassembled, rinsed thoroughly, and the friction linings must be cleaned with a steel brush or rasp;

wear of friction linings; if the wear of the pads is small, the malfunction is eliminated by adjusting the clutch pedal free play; if the linings are heavily worn, they must be replaced with new ones;

breakage or loosening of pressure springs; the springs must be replaced.

The clutch is not completely disengaged. A sign of this malfunction is the inclusion of a gear, accompanied by a sharp metal grinding of the gears of the gearbox, and the possibility of their breakdown is not excluded. Such a clutch malfunction can occur when following reasons:

large gap... between thrust bearing release clutches and inner ends of release levers; eliminate this malfunction by adjusting the free travel of the clutch pedal;

skew or warping of the driven discs and, as a result, an unequal gap between the discs (and in selected locations no gap); this malfunction most often occurs when the clutch overheats after slipping and is eliminated by replacing warped discs;

breakage of friction linings, as a result of which the torn lining is wedged between the driven and driving discs and does not allow the clutch to be completely disengaged; the clutch must be disassembled and the linings replaced;

misalignment of the pressure plate; when the clutch is disengaged, the drive disc continues to partially press against the driven disc. Such a malfunction occurs when the inner ends of the clutch release levers are not in the same plane; in this case it is necessary to adjust the position of the clutch release levers.

The clutch engages sharply despite the slow and smooth release of the pedal; the car jerks off. Such a malfunction can be in the event of a sticking of the release clutch on the guide sleeve. When the clutch pedal is released, the clutch will move unevenly along the bushing, when the force of the springs overcomes the binding of the clutch, it will quickly move, abruptly freeing the release levers, and the discs will quickly compress. Sharp engagement of the clutch can also be caused by small cracks on the drive discs after they are overheated. To eliminate the indicated malfunctions, replacement of the corresponding parts is required.

Basic clutch maintenance work. EO. Check the operation of the clutch mechanism by starting the vehicle and shifting gears while driving.

TO-1. Check the pedal free play (and, if necessary, adjust it), the condition and fastening of the retractor spring. Lubricate (according to the lubrication schedule) the clutch pedal shaft and the clutch release bearing. Check the clutch function.

TO-2. Check the full and free travel of the clutch pedal and the action of the return spring, the operation of the clutch drive and, if necessary, adjust the clutch and drive.

The bearing of the clutch release on the GAZ-53A and ZIL-130 cars of the first graduates is lubricated from an oiler filled with grease, for which it is necessary to screw the oiler cover two or three turns. On cars ZIL-130 ( latest issues) grease is added to the bearing of the clutch release at the factory and is not added during operation.

Clutch faults make it difficult to drive, distract the driver from observing the road, and interfere with the movement of other vehicles.

Transmission and transfer case malfunctions. A number of malfunctions can occur in the gearbox: chipping or breakage of gear teeth, spontaneous disengagement of gears, noise of gears during operation, simultaneous engagement of two gears and difficult gear shifting. All this worsens the conditions for safe traffic.

Chipping and breakage of gear teeth can occur as a result of a sharp start from a loaded car, with inept gear shifting and faulty clutch... Operation of the gearbox with broken gear teeth is unacceptable, as this can lead to the destruction of the entire gearbox.

Spontaneous shutdown transmissions possible due to uneven wear gear teeth and synchronizer couplings, incomplete gear engagement and wear of the locking device. The noise of the gears when shifting gears is due to a malfunction or improper clutch adjustment and inept engagement. Loud noise gears while driving is caused by lack of lubrication, heavy wear of gears, or bearings.

Basic maintenance work on the transmission and transfer case. EO. Check the operation of the transmission while driving.

TO-1. Check and, if necessary, tighten the gearbox mount; if necessary, add oil to the level. Check the operation of the transmission after servicing.

TO-2. Carry out an in-depth inspection of the transmission. Check and, if necessary, tighten the gearbox mount to the clutch housing and gearbox housing cover. Check and, if necessary, tighten the fastening of the bearing cover of the driven and intermediate shafts.

Top up or replace gearbox oil (per lubrication schedule).

Oil change, lubrication of units and joints must be carried out when idle engine... If the driver or locksmith is under the car, a sign "Do not start the engine!" Must be posted in the cab (on the steering wheel). The car must be reliably braked so that it cannot move spontaneously.

V / Malfunctions of the cardan and main gears, differential and "semi-axles. As a result of the car operating in the cardan transmission, wear of bearings, universal joints and a sliding splined coupling, bending or twisting of the cardan shaft is possible. Disconnection of the cardan shaft can lead to an accident. //" "

In the main gear and differential the following is possible: wear or breakage of the gear teeth; wear of the differential cross and bearings; wear or damage to oil seals; oil leakage in the rear axle housing connections. In the axle shafts, their twisting, wear of the splines, the loosening of the nuts of the axle shaft flange to the hub, or breakage of the studs are possible. A sign of a malfunction of the driveline are jerks and bumps when starting off or shifting gears on the move. Shaft runout during rotation indicates that the shaft is bent. "

Main gear malfunctions are externally manifested by significant noise in the rear axle housing when the vehicle is moving.

Driveshaft malfunctions are eliminated by restoring or replacing worn parts. The bent shaft must be corrected. Small clearances in the bearings and between the teeth of the final drive are eliminated by adjustments that must be made by experienced mechanics. In case of heavy wear of parts of the main person and differential, they must be replaced.

Worn axle shaft oil seals can lead to the ingress of grease into brake drums and the failure of the brakes, therefore, worn out oil seals must be replaced. In the event of a breakdown of the gear teeth of the main gear and differential, independent movement of the car is impossible.

Basic maintenance work on the cardan and main gears, differential. EO. Check the operation of the cardan AND main gear when the car is moving.

TO-1. Check and, if necessary, fasten the flanges of the universal joints and axle shafts. Secure final drive housing covers. Check the oil level in the drive axle housing and top up if necessary. Lubricate universal joints and suspension bearing (according to the lubrication schedule).

TO-2. Check for any play in the cardan joints. Fasten the flanges of the axle shafts, cardan shafts and the support bearing to the frame.

Check the tightness of the drive axle connections. Check the oil level or replace the oil in the drive axle housing.

Lubricate the driveline splined coupling (according to the lubrication schedule). The cardan crosspieces are lubricated with summer or winter transmission motor-tractor oil according to the lubrication chart (in the latest releases of ZIL-130 and KamaAZ vehicles grease 158 or US-1) using a syringe with a tip through an oiler until oil starts to come out of the hole, closed by valve from the side opposite to the grease nipple (for ZIL-130 cars of the latest releases and for KamAZ - from under the oil seals of all four crosspieces).

The splined cardan coupling is lubricated with US-1 or 1-13 grease (GAZ-53A and ZIL-130) at every third TO-2. Apply a moderate amount of grease to the splined coupling to prevent the plug from being pushed out. "In GAZ-53A cars, the intermediate support bearing must be lubricated with grease 1-13 at each TO-1, and in ZIL-130 at the second TO-1. On dusty and dirty roads, lubrication times are halved.

To lubricate the main gear of ZIL-130 vehicles, summer and winter auto-tractor transmission oil(TAP-15, TAP-10), GAZ-53A - TS-14.5 oil with "Chlo-ref-40" additive, KamAZ -TSp-15k or Tap-15V.

The oil level in the drive axle crankcase is checked after 3000 km of run. The oil level should be at the edge of the filler hole. The oil in the drive axle crankcase is changed according to the lubrication chart and when the operating season changes. Long-term operation of the final drive and thrust bearings largely depends on the quality and purity of the oils. The use of other oils is not allowed. Before pouring fresh butter the drive axle housing must first be flushed with liquid oil or kerosene. To do this, after draining the used oil (the oil should be drained heated immediately after work), 2-3 liters are poured into the crankcase liquid oil or kerosene, raise the drive axle to the goats, start the engine and, turning on the direct transmission, let it run for 1-2 minutes, then drain the oil or kerosene, tightly close the drain plug and fill in fresh grease at the level of the filler (control) hole. Oil is poured into the crankcase of the rear axle of cars in the amount of: ZIL-130 - 4.5 liters, GAZ-53A - 8.2 liters, KamAZ - 6 liters into each drive axle.

Running gear malfunctions. As a result of overloading and careless driving, the frame may bend, cracks and rivets may loosen in it. The frame is repaired in the workshop, the bent frame is corrected, the loosened jaws and frame parts that have cracks are replaced.

To the main malfunctions of the front and rear axles include: curvature of the front axle, wear of pins and pivot bushings, improper adjustment or wear of bearings, bearing breakage, development of bearing cage seating sites, broken thread of half-axle studs: A bent front axle, worn pins and bushings, improper adjustment or wear of wheel bearings drive To incorrect installation wheels, as a result of which it becomes difficult to control the car and increases tire wear, which negatively affects traffic safety, the bent axle must be straightened, worn pivots, bushings and wheel bearings must be replaced.

The front wheel bearings are adjusted in the following sequence: the front axle is raised and installed on the trestle, the wheel is removed, the cap is unscrewed, the nuts are unpinned and unscrewed, the hubs are removed, the bearings are washed and inspected (if there is a crack or significant wear, the bearings are replaced), the hub is filled with grease and put in place, install the washer and screw the nut to failure, and then unscrew it at a turn. The wheel should rotate freely, without jamming and have no backlash. After checking, the nut is pinned and the cap is screwed on.

On trucks, the rear wheel bearings are adjusted in the same sequence, except that instead of the cap, you need to unscrew the nuts of the axle studs and remove the axle shafts, and instead of removing the cotter pin, you need to unscrew the lock nut and remove the lock washer. Defective wheel hubs are handed over for repair or replaced with new ones. Driving with faulty hubs can lead to accidents.

As a result long-term work spring sheets partially lose their elasticity, pins and bushings wear out. When driving carelessly, leaf springs break. Springs that have lost their elasticity flex more than usual, as a result of which the tires rub against the body and wear out quickly. In addition, such springs break easily.

Driving with a broken leaf spring can lead to axle tilt and difficult steering. A spring that has lost its elasticity or with broken sheets is replaced.

In the shock absorber, oil seals, pivot joints, valves and springs wear out. As a result of wear of the oil seals. the bone leaks out and the shock absorber's performance deteriorates sharply. The defective shock absorber must be returned for repair.

As a result of careless driving, the discs or rims can be bent in the wheels. With loose studs and wheel nuts, the holes of the discs for the fastening studs wear out and the discs become unusable. Defective wheels are returned for repair. Driving with faulty wheels is dangerous.

Basic maintenance work on the undercarriage. EO. Check the condition of the frame, springs, springs, shock absorbers, wheels by inspection.

TO-1. Check and, if necessary, adjust the wheel hub bearings; check and, if necessary, secure the ladders, spring pins and wheel nuts. Lubricate (according to the lubrication schedule) spring pins and pivot pins. Check the condition of the vehicle's front suspension.

TO-2. Check the condition of the beam by inspection front axle... Check and, if necessary, adjust the amount of toe-in of the front wheels. In case of intensive tire wear, check the pivot angles and the steering angle of the front wheels. Check if there is a misalignment of the front and rear axles (visually).

Check the condition of the frame and the towing device, the condition of the springs, fasten the spring clamps, ladders, spring pins.

Check the condition of the shock absorbers, discs and wheel rims.

Lubricate (according to the lubrication schedule) pivot pins and spring pins. Remove the hubs, rinse, check the condition of the bearings and, changing the grease, adjust the wheel bearings.

Toe-in is checked using a ruler or on a stand. To check the wheel alignment with a ruler, the car is placed on the inspection ditch so that the position of the wheels corresponds to the movement in a straight line. The ruler measures the distance between the tires or wheel rims behind the front axle; the ruler is placed below the axle of the wheels (at the height of the ruler chains) and mark | chalk touch point. Then the car is rolled so that the chalk-marked points are set at the same height in front, and again measured. The figure indicating the difference between the first and second measurements is the toe-in value.

When inspecting, maintaining and repairing the undercarriage, follow the safety instructions. When installing the springs, do not allow fingers to check the coincidence of the holes in the spring and the bracket ears, as this can lead to injury. During the assembly of the spring after lubrication, it is necessary to properly fix it in a vice so that the sheets, straightening, do not cause injury.

Tire faults. Holes or punctures of tires with sharp objects, delamination of the carcass, peeling of the tread, destruction of the bead ring, puncture or rupture of the chambers - all these defects, as a rule, are the result of careless driving, non-observance of air pressure in tires and failure to comply with the rules of maintenance car tires... To repair tires en route, the vehicle must have a first aid kit.

The damaged tire must be removed and checked carefully. Stuck nails and other items must be removed. In case of large holes in the tire, it is necessary to put a cuff made of two or three layers of a piece of the frame of a waste cover or from a piece of rim tape. The damaged tire must be returned to the garage for repair. To restore the protector, tires are taken that do not have delamination of the carcass and through holes. To detect small punctures in the camera, it is pumped with air and immersed in water. Air bubbles will emerge at the site of damage.

Punctures or minor damage along the way can be repaired with a rubber patch. A section of the camera in a radius of 20 ... 30 mm around the damage is cleaned with a rasp or a steel brush and patches of raw rubber are applied, a cup with a vulcanization briquette is applied and clamped with a clamp (Fig. 198). The briquette is loosened and ignited, after complete combustion briquette after 10 ... 15 minutes, unscrew the clamp screw and take out the camera.

Temporary sealing of chamber punctures in the absence of vulcanization briquettes can be done with a patch from the waste chamber using rubber glue.

The edges of the patch are tapered. The patch and the area of the chamber around the damage are thoroughly cleaned with a metal rasp or a steel chute with a volcano-brush, remove dust, washed with gasoline and dried, then coated twice with rubber glue and dried after each coating for 15 ... 20 minutes. After drying, the patch is applied to the damaged area and rolled.

Basic tire maintenance work. EO-1. Clean tires from dirt and check their condition.

TO-1. Check the condition of the tires, remove foreign objects stuck in the tread and between the twin tires, the air pressure in the tires and, if necessary, pump air into them,

TO-2. Inspect the tires by removing any stuck objects in the tread. Check the air pressure and bring it back to normal. Rearrange the wheels according to the diagram. Have damaged tires repaired.

The serviceability of the tires is a prerequisite for the safe operation of the driver on the line. The absence of a tread pattern impairs the braking capabilities of the car, therefore, it is prohibited to use tires with a worn out tread pattern.

A prerequisite the operation of the car is also the reliability of the tires. Holes, as well as a rotted carcass, can lead to tire rupture during vehicle movement and an accident. Riding on semi-flat tires, in addition to them rapid wear, is dangerous due to the vehicle being pulled to the side.

clutch box gimbal transmission

Preparation for work and the procedure for carrying out maintenance

Preparation for maintenance consists in carrying out necessary work related to bringing the car into proper form. The required list of work for each type of maintenance is described in the next section of the manual. Maintenance is carried out in points or areas of maintenance or in specially equipped rooms that provide maintenance personnel the necessary conditions work.

According to the frequency, volume and labor intensity of the work performed, maintenance is divided into the following types:

Daily maintenance (EO);

First maintenance (TO - 1);

Second maintenance (TO - 2);

Seasonal maintenance (CO).

The frequency of the first and second maintenance depends on the category of vehicle operating conditions, determined by the type and condition highways... The characteristics of the categories of operating conditions and the frequency of maintenance - 1 and maintenance - 2 are carried out in table 1

Table 1

At daily maintenance(EO) checks the clutch, gearbox, propeller shafts and consists in cleaning from dirt, tightening bolted connections, adjusting and lubricating. After driving on muddy roads, clean the hole in the lower part of the clutch housing. Timely lubricate the clutch release bearing through the grease cap located with right side clutch housing.

At TO - 1 every 4000 km of run, or annually, with elevated level noise, when a leak occurs, the oil level in the gearbox is checked.

To check the oil level in the manual transmission, the vehicle must be parked on inspection pit, clean the area around the cork filler neck, unscrew and remove the plug. The oil should reach the bottom of the hole. If you need to check the oil level, you can insert a clean piece of flexible wire inside the box.

At reduced level need to top up special oil for manual transmissions. It is undesirable to exceed the level, since it can flow out over the edge of the hole.

In case of replacement, it is necessary to drain the oil while hot, by unscrewing the drain plug and first placing a container of the required volume under the gearbox. After that, the drain plug should be reinstalled, replacing the sealing washer, if necessary (it is advisable to change the washer each time the plug is unscrewed). Then fill in new oil and replace the filler plug.

At TO - 2 the clutch mechanism is checked is carried out with the clutch pressure plate removed in the following sequence:

1. Installed between the plate and the pressure plate, the template of the driven disk in the form of a ring with a thickness of 9.5 mm. The assembled pressure plate is fastened to the casing on the plate with six bolts.

2. Adjustment is carried out by screwing and unscrewing the stop bolts to obtain the size 51.5 ± 0.75 mm- distance of bolt heads from the surface of the plate (Fig. 13). The difference in the distance from the plate to the bolt heads should not exceed 0.2 mm.

3. The lever bolts are locked after adjustment, the edge of the lever is bent into the groove of the bolt shank, as shown in (Fig. 14)

Maintenance of the clutch release drive is reduced to adjusting the free travel of the release pedal, maintaining the level working fluid in the reservoir of the main cylinder of the hydraulic drive.

Front axle maintenance consists of maintaining required level oil in the crankcases and its timely change, checking the seals, timely detection and elimination of the 1st axial clearances in the gears of the main gear, in periodic cleaning safety valve and in the tightening of all bindings.

Removing the flange 35 (fig. 12) is made with the same bolts I with which it is attached.

Fill only the recommended oil into the housings of the final drive and wheel reduction gears and change it in strict accordance with the lubrication table.

Make sure that the oil level in the crankcases is at the lower edges of the filler holes.

The oil is drained through drain holes located »at the bottom of the crankcases, while unscrewing the filler plugs.

Rice. 12.

1 - clutch cover; 2 - pressure spring; 3 - pressure disk; 4 - thrust bolt; 5 - pull-off lever

Rice. 13.

For seasonal maintenance (CO). Front summer season technical operation replace the oils in the gearbox, front and rear axles with the flight grade, similarly to replace the oils in the winter.

Transmission units: clutch, gearbox (GB), hydromechanical transmission (GMT), cardan transmission, drive axles account for 15 ... 20% of failures and 20 ... 30% of material and labor costs for their elimination. This is due to the fact that the main working parts of the transmission are under the influence of high specific alternating loads most of the time.

The main clutch malfunctions are: lack of free play of the clutch pedal of functional pads; loosening of springs; incomplete disengagement of the clutch due to large free travel; skewed levers or warpage of the driven disc; heating, knocking and noise due to the destruction of the shutdown bearing; loosening of the rivets of the disc lining; breakage of damper springs; wear spline connection.

The malfunctions of the cardan transmission include: shaft runout, increased gaps in the joints, which is accompanied by vibration, knocking and noise during operation, especially when shifting gears in acceleration mode.

Typical malfunctions mechanical gearbox, transfer case, main gear are: self-shutdown of the gear due to misalignment of the drive, wear of bearings, teeth, splines, shafts, retainers; noises and knocks when shifting gears due to synchronizer malfunctions; increased vibrations, heating, backlash due to wear or breakage of gear teeth, wear of bearings, misalignment of gearing of gear pairs, low level or lack of lubrication in gearboxes.

To the main faults hydromechanical box gears include: non-inclusion of gears when the car is moving due to failure of electromagnets, jamming of the main spool, failure of hydraulic valves, misalignment of the system automatic control gear shifting; inconsistency of the gear shift points due to misalignment of the automatic gear change system or malfunctions of the power and centrifugal regulators; low oil pressure in the main line due to wear of parts oil pumps or internal leaks transmission oils; elevated temperature oil on the drain from the torque converter due to warpage or wear of the clutch discs.

For front wheel drive passenger cars additional malfunctions may occur: damage to the covers covering the constant velocity joints (SHRUS); deformation drive shafts; wear of the hinges themselves.

In general diagnostics of the transmission, mechanical losses due to spinning of the driving wheels are determined by the traction stand, the smoothness of gear engagement, noise and knocks during the operation of transmission elements, and the amount of their heating are assessed.

With element-by-element diagnostics, the technical condition of each of the units is determined.

Technical condition The clutch is quite fully determined by the amount of free travel of the pedal, the completeness of the clutch release and its slipping. Pedal free play is measured with a ruler or special devices type KI-8929. In this case, the pedal is pressed by hand, moving it from its initial state to the occurrence of effort on the pedals. For most cars, it should be within 15 ... 45 mm (cars with mechanical or hydraulic drive clutches). If the free play does not match, it is adjusted by changing the gap between the ends of the pressure levers and release bearing, for which a threaded adjustment unit is provided in the drive rod. The completeness of the clutch release is assessed by the ease of gear engagement.

Clutch slip is determined when the car is operating under load on the traction bench using an electronic stroboscope included in the ignition system circuit or using a stroboscope connected to the injector of the first cylinder (for a diesel engine).

At the time of filing high voltage pulses are applied to the spark plug of the first cylinder or by fuel injection to the stroboscope, leading to discrete flashes of the stroboscopic device lamp, carried out synchronously with the rotation of the engine crankshaft. In the absence of clutch slipping, the driveshaft, illuminated by the strobe lamp flashes, will appear stationary, as it rotates with crankshaft as one whole. If the propeller shaft rotates perceptibly in the light of the strobe lamp, then the clutch slips. It is advisable to carry out such a check in conjunction with the assessment of the power properties of the car. The hydraulic or pneumatic clutch is assessed for tightness.

The technical condition of the gearbox is determined by its thermal state, noises, knocks, vibrations, by the total angular play in each gear and by inspection with an endoscope.

The thermal state of the gearbox is determined using special thermometers after the vehicle returns from the line so that the transmission units do not cool down. The temperature should not exceed 35 ... 50 ° С. Large values indicate the presence of wear or insufficient oil in the gearbox housing. When diagnosing noise and vibration parameters, stethoscopes are used. This method combined with listening to the characteristic noises of the transmission elements when simulating the movement of the car on the traction stands at low load. In this case, the ease of gear shifting, places of increased heating, etc. are additionally revealed.

The total angular backlash in gears is determined using a dynamometer-backlash (Figure 2.44). With the help of clamp 1, it is attached to the flange of the universal joint cross, connected with secondary shaft KP. Press the handle 9 with a force of 15 ... 25 N × m, fixed on the scale 8 of the dynamometer and note the position of the bubble of the liquid level 4 on the angular scale 5. Then press the handle 9 with the same force in opposite side so that the gaps are selected and the total angular gap is determined by the liquid level and scale 5. The check is carried out with sequential engagement of all gears. The value of the total angular backlash in gears should not exceed 6 ... 10 °. Large values of the backlash indicate the presence of wear in the gear pairs.

Diagnostics of hydromechanical transmissions is carried out at the traction bench with the setting of the necessary speed and load modes - acceleration, braking, steady motion in each gear. In this case, portable devices are used that are connected to the electromagnets of the first and second gears, to the oil supply line from the main spool to the torque converter lock-up valve. Here are also determined the moments of gear shifting in terms of speed with a smooth "acceleration" of the car on the unloaded rollers of the stand. In this case, the switching points are determined by the vibrations of the speedometer needle.

1 - screw terminal; 2 - movable jaws; 3 - crosspiece flange; 4 - liquid level; 5 - angular limb; 6 - spring; 7 - arrow of the dynamometer; 8 - dynamometer scale; 9 - handle

Figure 2.44 - Diagram of a dynamometer-backlash

The GMF mechanisms are adjusted using a special screw, changing the position of the main spool to ensure the required modes automatic switching gears (for example, for the GMF of the LiAZ bus during acceleration with a fully open throttle switching from a downshift to a straight line should take place at a speed of 25 ... 30 km / h, a torque converter lock - at a speed of 35 ... 42 km / h). The stroke of the end of the longitudinal control rod of the power regulator control and the clearance in the control mechanism of the spools of the peripheral valves are also regulated in order to reduce the wear of the double clutch discs during operation.

The cardan drive is diagnosed by radial runout. In this case, one drive wheel is hung out and with the help of the device it is determined radial runout(Figure 2.45). It is equal to the difference between the maximum and minimum values of the displacement indicator readings when the propeller shaft is rotated 360 ° (for this, the suspended wheel is manually scrolled). Permissible value runout for trucks is 0.9 ... 1.1 mm, for cars - 0.4 ... 0.6 mm. Wear in hinges and spline joints is assessed visually by their relative movement when turning the propeller shaft in both directions manually. There should be no perceptible backlash and knocking. The total angular backlash can also be measured using a backlash dynamometer. In this case, one end of the cardan transmission must be pinched (for cars such as GAZ, ZIL, it is used parking brake). Its value should not exceed 2 ... 4 °.

Driving axles are diagnosed using the same parameters and the same means as mechanical boxes gear. The total angular backlash for single main gears should be no more than 35 ... 40 °, for double - 45 ... 60 ° (when checking the gearbox must be in neutral).

1 - cardan shaft; 2 - indicator tip; 3 - a tripod with stops; 4 - indicator of linear movements

Figure 2.45 - Diagram of the device for checking the runout of the propeller shaft

These works can be carried out in parallel with preventive operations. So with TO-1, the free travel of the clutch pedal and the tightness of the hydraulic or pneumatic drive should be checked. The gearbox checks the operation of the gearshift mechanism when the vehicle is stationary. According to the GMF, the correctness of the adjustment of the control mechanism for the peripheral spools is checked. The cardan transmission is used to check the backlash of the hinged and spline joints, the condition of the intermediate support. In addition, during TO-1, the fasteners of the transmission elements and the tightness of the gearbox and drive axle connections are checked. With TO-2, in addition, according to the GMF, the correctness of the adjustment of the gear shift modes, the oil pressure in the system and the serviceability of the oil temperature sensor are checked, along the drive axle - the fastening of the nut of the flange of the main gear drive gear (with the cardan shaft removed).

When servicing the front wheel drives, they are limited to inspecting them and listening to noises and knocks in the CV joints when the wheels are spinning. When a malfunction is detected, unusable elements ( rubber covers, SHRUS) are replaced. When replacing the SHRUS, grease SHRUS-4 (ULi 4/12-d2) is put into it, which is not replenished until the next replacement.

Work on the restoration of transmission units is performed in the unit section after they have been dismantled from the vehicle. The clutch is removed after dismantling the gearbox, as a rule, together with the casing, having previously disconnected its drive. After removal, the pressure and driven discs are cleaned.

The driven disc is defective for wear of the friction plates and runout. Replace worn-out pads with new ones. When the end runout of the driven disk is more than 1 mm, it is straightened. For all other malfunctions, the driven disc is replaced. The pressure disk is discarded if it is significantly worn out or other defects. Clutch installation is carried out in the reverse order of disassembly. To center the driven disc relative to the flywheel, use a special splined mandrel or an auxiliary input shaft of the gearbox, inserting it into the spline of the driven disc and the crankshaft flange bearing. Then the clutch cover is finally tightened to the flywheel. Moreover, it is necessary to tighten gradually and consistently in 2 ... 3 receptions. If the clutch is hydraulically operated, it is pumped to remove air, and then the pedal free travel is adjusted.

When repairing the gearbox, the oil is drained from it. Then the gearbox is removed from the car, subjected to external cleaning and washing, and delivered to the aggregate section. Initially, the gearbox cover with the gearshift mechanism is removed. To press out the input shaft, use a special tool (Fig. 2.46).

Figure 2.46 - Tool for pressing out the bearing input shaft

The output shaft bearing together with the shaft is pressed out with a hammer using a mandrel. Intermediate shaft pressed out with a puller. For disassembly intermediate shaft special devices are also used. After final disassembly, all parts are washed in kerosene or detergent solution (if there is an installation for parts washing) and are defective. Worn out elements are replaced.

Gearbox assembly is carried out in the reverse order of disassembly. All gaskets are recommended to be installed on rubber # 80. After installation on the vehicle, the gearbox is filled with gear oil according to the lubrication chart.

The cardan transmission is also repaired in the unit compartment, having previously subjected it to external cleaning and washing. It is advisable to disassemble the hinges using a special tool (Figure 2.47). It is carried out in two steps. First, one of the forks is installed on the supports and the needle bearings are pressed out of it. Then the propeller shaft is turned 90 ° and the bearings are pressed out of the second fork. The same puller can also be used to install bearings in which 4 ... 5 grams of grease No. 158 (ULi - PG 4 / 12-1) or Fiol-2M (ILi 4/12-d2) are preliminarily laid. If the hinges have grease nipples, then they are lubricated with a solid blower after assembly. When disassembling the splined joint of the cardan transmission, marks are made so that its balance is not disturbed during assembly.

a - extrusion of bearings from the sliding fork; b - pressing out the bearings from the propeller shaft plug

Figure 2.47 - Disassembly tool cardan joint

Dismantling the rear axle truck it is advisable to carry out also after removing it from the vehicle assembly. In passenger cars, as a rule, only the gearbox is removed. After external cleaning and washing, the fastening bolts are unscrewed and removed main gear... Removal of the bearings of the drive gear shafts and the bearings of the differential cup is carried out using a puller (Figure 2.48). After disassembly, all parts are subjected to washing and troubleshooting. Worn out elements are replaced.

Before assembly, all bearings are lubricated with Litol-24 (MLi 4 / 12-3) and pressed using mandrels. For the normal installation of the gearing of the gear teeth, oil paint is applied to them in a thin layer along the contact patch. Then the shaft of the driving bevel gear is turned in one direction and the other, braking the driven gear by hand.

1 - screw; 2 - traverse; 3 - screed; 4 - screed cheek; 5 - capture; 6 - tip

Figure 2.48 - Removing the bearing of the differential cup

The position of the contact patch is used to assess the nature of the engagement (Table 2.6).

The contact patch is adjusted by axial movement of the driven and driving gears, for which the installation of adjusting shims is provided in the design of the main transmission. The degree of tightening of the bearings of the pinion drive shaft is checked using a dynamometer (Fig. 2.49).

Position of the contact patch on the wheel	Ways to Achieve Correct Gear Meshing	Direction of movement of gears
Forward course	Reverse
	Correct contact
	Nudge gear to the gear. If this results in too little lateral clearance between the teeth, move the gear
	Move the toothed wheel away from the pinion. If this results in too large a lateral clearance between the teeth, move the gear
	Move the gear to the wheel. If the side clearance is too small, move the gear back
	Move the gear away from the wheel. If the side clearance is too large, move the gear

1 - cover; 2 - bearing housing; 3 - leading bevel gear; 4 - vice; 5 - dynamometer; 6 - flange; 7 - nut

Figure 2.49 - Checking the tightening of the bearings of the drive gear shaft

The torque of the drive gear shaft should be no more than 1.0 ... 3.5 N × m, when tightening the flange mounting nut 7 with a torque of 200… 250 N × m. The adjustment is also carried out using the adjusting shims provided by the design of the main gear. After final assembly, the main gear is installed on the car and transmission oil is poured into the rear axle housing according to the lubrication chart.

Typical malfunctions of a mechanical gearbox, transfer case, main gear are: self-shutdown of the gear due to misadjustment of the drive, wear of bearings, teeth, splines, shafts, retainers; noises and knocks when shifting gears due to synchronizer malfunctions; increased vibrations, heating, backlash due to wear or breakage of gear teeth, wear of bearings, misalignment of gearing of gear pairs, low level or lack of lubrication in gearboxes.

The main malfunctions of a hydromechanical transmission include: failure to engage gears when the vehicle is moving due to failure of electromagnets, jamming of the main spool, failure of hydraulic valves, misalignment of the automatic control system for gear shifting; inconsistency of the gear shift points due to misalignment of the automatic gear change system or malfunctions of the power and centrifugal regulators; low oil pressure in the main line due to wear of oil pump parts or internal oil leaks in the gear; increased oil temperature at the drain from the torque converter due to warpage or wear of the clutch discs.

For front-wheel drive cars, malfunctions may additionally occur: damage to the covers covering the constant velocity joints (SHRUS); deformation of drive shafts; wear of the hinges themselves.

With element-by-element diagnostics, the technical condition of each of the units is determined.

The technical condition of the clutch is quite fully determined by the value of the pedal free travel, the completeness of the clutch release and its slipping. Free travel of the pedal is measured using a ruler or special devices such as KI-8929. In this case, the pedal is pressed by hand, moving it from its initial state to the occurrence of effort on the pedals. For most cars, it should be within 15 ... 45 mm (cars with mechanical or hydraulic clutches have lower values). If the free play does not match, it is adjusted by changing the gap between the ends of the pressure levers and the release bearing, for which a threaded adjustment unit is provided in the drive rod. The completeness of the clutch release is assessed by the ease of gear engagement.

When a high voltage is applied to the spark plug of the first cylinder or injection by a fuel injector, pulses are supplied to the stroboscope, leading to discrete flashes of the stroboscopic lamp, carried out synchronously with the rotation of the engine crankshaft. In the absence of clutch slipping, the propeller shaft, illuminated by the strobe lamp flashes, will appear stationary, since it rotates with the crankshaft as a whole. If the propeller shaft rotates perceptibly in the light of the strobe lamp, then the clutch slips. It is advisable to carry out such a check in conjunction with the assessment of the power properties of the car. The hydraulic or pneumatic clutch is assessed for tightness.

The technical condition of the gearbox is determined by its thermal state, noises, knocks, vibrations, by the total angular play in each gear and by inspection with an endoscope.

The thermal state of the gearbox is determined using special thermometers after the vehicle returns from the line so that the transmission units do not cool down. The temperature should not exceed 35 ... 50 ° С. Large values indicate the presence of wear or insufficient oil in the gearbox housing. When diagnosing noise and vibration parameters, stethoscopes are used. This method is combined with listening to the characteristic noises of the transmission elements when simulating the movement of a car on traction stands at a low load. In this case, the ease of gear shifting, places of increased heating, etc. are additionally revealed.

The total angular backlash in gears is determined using a dynamometer-backlash (Figure 2.44). With the help of clamp 1, it is attached to the flange of the universal joint cross, connected to the gearbox output shaft. Press the handle 9 with a force of 15 ... 25 N × m, fixed on the scale 8 of the dynamometer and note the position of the bubble of the liquid level 4 on the angular scale 5. Then press the handle 9 with the same force in the opposite direction so that the gaps are also selected along the liquid level and scale 5 determine the total angular clearance. The check is carried out with sequential engagement of all gears. The value of the total angular backlash in gears should not exceed 6 ... 10 °. Large values of the backlash indicate the presence of wear in the gear pairs.

1 - screw terminal; 2 - movable jaws; 3 - crosspiece flange; 4 - liquid level; 5 - angular limb; 6 - spring; 7 - arrow of the dynamometer; 8 - dynamometer scale; 9 - handle

Figure 2.44 - Diagram of a dynamometer-backlash

The GMF mechanisms are adjusted using a special screw, changing the position of the main spool to ensure the required modes of automatic gear shifting (for example, for the GMF of the LiAZ bus when accelerating with a fully open throttle valve, switching from a downshift to a straight line should occur at a speed of 25 ... 30 km / h, blocking of the torque converter - at a speed of 35 ... 42 km / h). The stroke of the end of the longitudinal control rod of the power regulator control and the clearance in the control mechanism of the spools of the peripheral valves are also regulated in order to reduce the wear of the double clutch discs during operation.

The cardan drive is diagnosed by radial runout. In this case, one drive wheel is hung out and with the help of the device the radial runout is determined (Figure 2.45). It is equal to the difference between the maximum and minimum values of the displacement indicator readings when the propeller shaft is rotated 360 ° (for this, the suspended wheel is manually scrolled). The permissible runout value for trucks is 0.9 ... 1.1 mm, for cars - 0.4 ... 0.6 mm. Wear in hinges and spline joints is assessed visually by their relative movement when turning the propeller shaft in both directions manually. There should be no perceptible backlash and knocking. The total angular backlash can also be measured using a backlash dynamometer. In this case, one end of the cardan transmission must be pinched (for cars such as GAZ, ZIL, the parking brake is used). Its value should not exceed 2 ... 4 °.

Drive axles are diagnosed using the same parameters and the same means as manual transmissions. The total angular backlash for single main gears should be no more than 35 ... 40 °, for double - 45 ... 60 ° (when checking the gearbox must be in neutral).

1 - cardan shaft; 2 - indicator tip; 3 - a tripod with stops; 4 - indicator of linear movements

Figure 2.45 - Diagram of the device for checking the runout of the propeller shaft

When servicing the front wheel drives, they are limited to inspecting them and listening to noises and knocks in the CV joints when the wheels are spinning. If a malfunction is found, unusable elements (rubber covers, CV joints) are replaced. When replacing the SHRUS, grease SHRUS-4 (ULi 4/12-d2) is put into it, which is not replenished until the next replacement.

Figure 2.46 - Device for pressing out the input shaft bearing

The output shaft bearing together with the shaft is pressed out with a hammer using a mandrel. The intermediate shaft is pressed out with a puller. Special tools are also used to disassemble the intermediate shaft. After final disassembly, all parts are washed in kerosene or detergent solution (if there is an installation for parts washing) and are defective. Worn out elements are replaced.

a - extrusion of bearings from the sliding fork; b - pressing out the bearings from the propeller shaft plug

Figure 2.47 - Device for disassembling the universal joint

It is advisable to disassemble the rear axle of a truck also after it has been removed from the assembled vehicle. In passenger cars, as a rule, only the gearbox is removed. After external cleaning and washing, the mounting bolts are unscrewed and the main gear is removed. Removal of the bearings of the drive gear shafts and the bearings of the differential cup is carried out using a puller (Figure 2.48). After disassembly, all parts are subjected to washing and troubleshooting. Worn out elements are replaced.

1 - screw; 2 - traverse; 3 - screed; 4 - screed cheek; 5 - capture; 6 - tip

Figure 2.48 - Removing the bearing of the differential cup

The position of the contact patch is used to assess the nature of the engagement (Table 2.6).

Position of the contact patch on the wheel	Ways to Achieve Correct Gear Meshing	Direction of movement of gears
Forward course	Reverse
	Correct contact
	Slide the toothed wheel towards the pinion. If this results in too little lateral clearance between the teeth, move the gear
	Move the toothed wheel away from the pinion. If this results in too large a lateral clearance between the teeth, move the gear
	Move the gear to the wheel. If the side clearance is too small, move the gear back
	Move the gear away from the wheel. If the side clearance is too large, move the gear

1 - cover; 2 - bearing housing; 3 - leading bevel gear; 4 - vice; 5 - dynamometer; 6 - flange; 7 - nut

Figure 2.49 - Checking the tightening of the bearings of the drive gear shaft

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