The power steering ZIL 130 is PZ, drawings

1.1 Brief description of the repaired unit/mechanism/.

Steering with hydraulic booster.

It is used on medium and heavy vehicles. The hydraulic booster serves to reduce the driver's force on the steering wheel when turning the front wheels, mitigates the impacts arising from damage to the tires.

Steering consists of a steering gear combined in one unit with a hydraulic booster, a gearbox 10, a steering column with a steering shaft and a wheel (not shown) and components of the hydraulic system. The drivetrain installed between the steering gear and the steering shaft compensates for the influence of cab vibrations relative to the car frame. The steering body 2, cast from ductile iron, is simultaneously a hydraulic booster cylinder. It is bolted to the frame of the car.

Steering mechanism has two working pairs: screw 5 with nut 7 on circulating balls 6 and piston-rack 4 engaged with toothed sector 2 of nozzle shaft. Steering gear ratio 20:1. The steering screw 5 has an arched screw groove ground with great precision. The same groove is made in nut 7. Screw channel formed by screw and nut is filled with balls. Nut is rigidly fixed inside piston-rack. Toothed rack and toothed sector have variable teeth thickness, which allows adjusting clearance in rack-sector engagement with adjusting screw screwed into side cover of steering gear case. Flexible split cast iron rings are installed on piston-rack to ensure its tight fit in crankcase-cylinder 3. Rotation of the steering shaft is converted into translational movement of the piston-rack due to movement of the nut along the screw. Teeth of piston-rack turn sector as a result, and with it shaft with lug 1. Control valve with slide valve 2 is installed in front of steering case in housing 10. Hydraulic booster pump is connected with hose control valve B and D.

During straight movement of the car, the slide valve is in the middle position (as shown in the figure) and the oil from the pump 18 through the hose G through the control valve is pumped to the tank 19 through the hose B. When the steering wheel turns to the right, the screw with the slide valve 12 moves back (in the figure to the right) as a result of the interaction of the piston-rack teeth and the sector. Moving backwards, the slide valve opens oil access to the cavity B through the channel D. As a result of the oil pressure on the piston-rack, the force that is spent on turning the steering wheel is reduced. At that, steering nozzle turns counterclockwise. When the steering wheel is turned to the left, the slide moves forward and opens oil access to the cavity A along the channel E, as a result of which the rotation of the wheel to the left is facilitated. If the driver stops rotation of the steering wheel, the control valve spool will take the I middle position, and the angle by which the guide wheels are turned will remain unchanged.

Steering mechanism has screw with nut on circulating balls and rack with toothed sector. 1the steering gear transmission ratio is 20:1.

Steering mechanism is attached to frame and connected with shaft of steering column of cardan shaft with two hinges.

The steering crankcase 4 is simultaneously a hydraulic booster cylinder in which the piston-rack 5 is moved. Plug (3) is filled in piston-rack. The piston-rack engages the toothed sector of the steering nozzle shaft 31. The teeth of the rack and the nipple shaft have a variable length thickness, which allows adjusting the engagement gap by axial displacement of the nipple shaft.

The steering nozzle shaft rotates in bronze sleeves 33 pressed into the crankcase and in the opening of the crankcase side cover 24. The axial position of the nipple shaft is determined by an adjustment screw 30, the head of which enters the hole of the nipple shaft and rests on the thrust washer 26. The axial movement of the adjusting screw in the nozzle shaft, held during assembly within 0.06 mm, is limited by the adjusting washer 27 and the locking ring 28.

In the piston-rack there is a ball nut 8 fixed with mounting screws 42 locked after assembly. The nut is pre-assembled with the screw 7 in such a way that 31 balls 10 are inserted into the screw grooves and the chute.

Two stamped chutes 9 are inserted into the slot of the ball nut connected by two holes to its screw groove, forming a tube along which the balls, when the screw is turned from one end of the nut, return to its other end. The screw 7 extends through an intermediate cover 12 to which the control valve body 17 is attached. Two thrust ball bearings 13 with control valve spool 16 between them are installed on the screw: Large rings of ball bearings face the spool. Ball bearings and slide valve are secured by nut 19 whose thinned bead is pressed into slot on screw. A conical spring washer 18 is placed under the nut. providing constant preliminary compression of thrust ball bearings. Spring is installed with concave side to ball bearing.

Length of slide valve is larger than length of hole for it in control valve housing. As a result, the slide valve and the screw can move in the axial direction by 1 mm in each direction from the middle position. They return to the middle position under the action of six springs 39 and. reactive plungers 40 under oil pressure in the supply line from the pump.

The screw 7 rotates in a needle bearing 21 located in the upper cover 20 of the steering mechanism.

Two hoses from the hydraulic booster pump are connected to the control valve housing: high-pressure hose 4, through which oil is supplied from the pump, and low-pressure (drain) hose 3, through which oil is returned to the pump.

When the screw 7 rotates in one direction or the other, the resistance resulting from the rotation of the wheels creates a force tending to move it axially in the corresponding direction. If this force exceeds the pre-compression force of the springs 39, the screw moves and displaces the slide valve 16. Note here that one chamber of hydraulic booster cylinder communicates with pressure line and another chamber communicates with drain. Oil coming from the pump into the cylinder presses on the piston, creating an additional moment on the steering nozzle shaft, and contributes to the rotation of the wheels.

Pressure in cylinder working chamber increases with increasing resistance to wheel turning. Simultaneously, the pressure under the jet plungers 40 increases. The screw and spool tend to return to the middle position under the action of springs 39 and reactive plungers, as well as wheel stabilization forces.

The greater the resistance to turning the wheels and the higher the pressure in the working cavity of the cylinder, the greater the

ilium, with which the slide valve tends to return to the middle position and set the thrust ball bearings and the screw to the middle position, the greater the force on the steering wheel. When the force on the steering wheel increases with increasing resistance to turning the wheels, the driver creates a "sense of road."

The force on the steering wheel rim, corresponding to the beginning of the hydraulic booster, is about 2 kg, and the greatest force is about 10 kg.

When the steering wheel stops turning, the oil entering the cylinder, shifting the piston, sets the screw and spool to the middle position, which causes the further movement of the piston, and therefore the rotation of the wheels, to stop.

Control valve housing has ball valve 15 connecting high-pressure and drain lines at non-operating pump. In this case, the valve ensures the operation of the steering mechanism, as a conventional steering mechanism without a hydraulic booster.

Cavity containing thrust ball bearings is connected with drain and is sealed with rubber rings 14 of round section. Similar rings 2, 25 and 41 seal the remaining fixed joints.

The steering nozzle shaft 31 is sealed with a rubber seal 34 which has a thrust ring 35 to prevent it from being turned out under pressure. The outer rubber cuff 36 prevents dirt and dust from entering the shaft. Piston-rack is sealed with two cast-iron flexible split rings 11, locks of which must be located on opposite sides of piston-rack.

The steering screw 7 has two seals in the intermediate cover and in the piston-rack. The upper cover 20 seals the screw 1 with a rubber seal 38 with a thrust ring 22 and an outer collar 23. The adjusting screw 30 is sealed by a circular rubber ring 29.

When the steering screw 7 rotates in one direction or the other from the middle position, the free stroke in the steering mechanism increases. This is achieved by the fact that the thickness of the middle tooth of the nozzle shaft 31 is increased compared to the rest of the teeth, and the steering screw 7 has a barrel-shaped shape with a slight decrease in the diameter of the screw groove .to its ends.

The steering crankcase has a magnet plug 32 which captures steel and cast iron particles from the oil.

The steering screw 7 is connected to the steering column of the cardan shaft, whether there is air in the system, draft or dirt in the tank and on the pump filters and oil leakage in the pipeline connections.

1.2 Characteristic faults of the repaired unit.

Troubleshooting Manual Control

Steering malfunctions. These faults have the greatest impact on traffic safety, so if they are detected, they must be rectified immediately. The main malfunctions are an increase in the total play (free stroke) of the steering wheel, an increase in the force required for its rotation, knocks and noises in the steering mechanism.

When the steering wheel play increases, driving is difficult (the car "does not hold the road"). The reasons for this failure may be an increase in the clearances in the bearings of the hubs of the controlled wheels, in the hinges of the steering rods, in the bearings or in the engagement of the working pair (worm and roller of the GAZ5312 car, piston and gear sector of the ZIL cars) due to wear of parts and loosening of the attachment of the crankcase of the steering mechanism, steering stick and levers of the turning trunnions. In addition, in the GAZ5312 car, the reason for increasing the steering wheel play may be the loosening or breaking of the springs of the steering tips, and in the ZIL cars, the increase in clearances in the cardan steering joints and the loosening of the tightening of the wedges of the cardan shaft attachment.

The force required to turn the steering wheel increases and or becomes uneven when the steering bearings are jammed. damage of its parts, violation of clearance adjustment in engagement of the working pair, and for ZIL vehicles, in addition, with insufficient tension of the hydraulic booster pump drive belt, insufficient level of oil in hydraulic booster housing and pump tank, presence of air in hydraulic system, oil contamination, loosening of nut tightening of thrust bearings of steering screw, periodic hanging of bypass valve. If the suspension of the bypass valve is permanently or weakened by the attachment of the safety valve seat of the pump, the hydraulic booster stops working and the force required to turn the steering wheel increases sharply. The reason for lowering the oil level may be its leakage due to wear or damage to the sealing rings, the packing of the nozzle shaft, loosening of the connections of the hoses and hydraulic booster pipelines. It is possible to eject oil through the pump safety valve when its level is excessively high, the filter is clogged or damaged, the collector is deformed or its gasket is destroyed.

Knocks in the steering gear of the GAZ5312 car appear when the working surfaces of the worm or roller are destroyed, and in the steering gear of the ZIL cars - when the gap in the toothed engagement is increased. Increased noise during operation of the hydraulic booster pump is caused by low tension of the belt of its drive, decrease of oil level in the tank, when air enters the hydraulic system, clogging or damage of the filter, deformation of the manifold or destruction of its gasket.

How to detect steering faults. Before checking the steering control, the air pressure in the tires is adjusted to the norm, the installation angles and bearings of the hubs of the steered wheels are checked and, if necessary, adjusted, the attachment of the steering crankcase, steering nozzle and rotary trunnion levers is tightened, the presence of lubricant in the steering units and wheel hubs is checked, and in ZIL cars, the level and quality of oil in the hydraulic booster pump tank. The car is installed on a flat platform, and controlled wheels - in a position for straight movement.

The total play of the steering wheel and the force required for its rotation are determined using a luftometer dynamometer. Steering wheel play shall not exceed 20 °. The force required to turn the steering wheel in both directions from the middle position for the GAZ5312 should be 16... 22 N. In ZIL vehicles, the force is checked in three positions of the steering wheel when the engine is operating. In the first (steering wheel turned by more than 2 turns from the middle position) the required force 5.5... 13.5 N, in the second (steering wheel turned 3/4... 1 revolution from the middle position) not more than 23 H, in the third (steering wheel passes the middle position) by 8... 12.5 H more than in the second position, but not more than 28 N.

With an increased play of the steering wheel, its cause is determined by alternately turning the steering wheel to the right and left sides and at the same time checking the hinges of the steering rods and steering connections. Clearances in pivots of steering rods are determined by movement of fingers relative to tips or heads of steering rods.

Axial movement of steering wheel is determined by taking it by two hands and alternately moving it in axial direction on itself and from itself. Noticeable movement of the steering wheel indicates an increase in axial clearances in the bearings

steering.

To check the level and quality of oil in the tank of the hydraulic booster pump, the controlled wheels of the car are installed directly and the cover is removed from the tank, having previously cleaned it from dirt and washed with gasoline. When the engine is operating in idling mode, the upper oil level must be above the net of the fill strainer. Cloudy oil and foam in the tank indicate air ingress into the hydraulic system.

Oil pressure is checked during engine idling with low crankshaft speed and at oil temperature 65... 75 ° С. To check between the hydraulic booster pump and the high-pressure hose, an accessory is installed, having a pressure gauge and a valve, which cuts off the oil supply to the amplifier. Open the valve, turn the steering wheel until stop with force not less than 100 N. Oil pressure must be not less than 6 MPa. At -less pressure, the valve is wrapped, following the readings of the pressure gauge. If the pressure rises to 6.5 MPa, the pump is serviceable, the steering mechanism is not. If it rises, but does not exceed 6 MPa, both the pump and the steering mechanism are faulty. Ways to troubleshoot steering failures. When clearances in hinges of longitudinal rods are increased, they are adjusted by tightening threaded plugs 15 and 21 (refer to Figure 9.5) until stop, after which they are released to the first possible position for cotter pin, but not more than by 1/4 turn, and cotter pin. When clearances in joints of transverse rods are increased, they are not adjusted, but replaced by worn-out parts (pins, inserts, springs). To adjust the axial clearance in the bearings of the worm (GAZ5312), the steering mechanism is removed from the car and oil is drained from its crankcase. The lower cover 8 of the steering case is then removed (see Figure 9.1) and one thin gasket 2 is removed. After the cover (3) is installed in place, the presence of axial clearance in the worm bearings is checked. If it is not eliminated, then replace the thick gasket with the previously removed thin one. The total thickness of the gaskets is reduced until then; until the axial clearance is selected.

The engagement of the worm with the roller is adjusted by screwing the adjusting screw 9 into several cuts with a special wrench.

lock washer.

If there is axial movement of the steering wheel of ZIL vehicles, the steering shaft is disconnected from the cardan shaft and the edge of the lock washer antennae is bent so that it leaves the slot of the adjusting nut 5 (Fig. 9.6, a). The adjusting nut is tightened until the moment of rotation of the steering shaft is equal to 30... 80 - m. The moment of rotation is measured with a dynamometer 4. Excessive tightening of nut (5) with its subsequent screwing is not allowed, as this can cause damage to bearings.