Removing the steering mechanism from the car
To remove the steering gear from the vehicle, do the following:
- - set the front wheels straight;
- - disconnect the steering column cardan shaft yoke from the input shaft, for which unscrew the coupling bolt;
- - unpin and unscrew the bipod mounting nut on the shaft and remove the bipod from the shaft using a special puller (Fig. 1), without disconnecting the longitudinal link from the bipod as follows:
- - unpin and unscrew the sector shaft nut. Install the puller so that the gripping shoulder of the puller housing 1 is located between the steering gear housing and the bipod. Remove the bipod 3 by turning the screw 2 using a wrench.
- - disconnect the hoses from the distributor, after draining the oil from the tank and the steering gear housing;
- - unscrew the bolts securing the steering gear to the frame bracket and remove the steering gear.
Disassemble the steering mechanism in the following sequence:
- - remove the distributor, having previously marked the relative position of the housing 1 of the steering mechanism (see Fig. 2), the housing 6 of the distributor cover 9 of the distributor.
It is recommended to remove the distributor using a simple tool.
To do this, unscrew the bolts 10 for fastening the distributor and two opposite bolts 23, which secure the base of the fixture to the stuffing box cover 22, abut the fixture screw through the ball into the torsion bar so that the pin 19 freely passes along with the input shaft 18, and then, screwing the screw tools, remove the distributor.
If there is no device, the distributor can be removed as follows - unscrew the bolts 10, turn the distributor housing 6 so that the holes in it do not coincide with the holes in the steering mechanism housing 1 and, screwing two special bolts (Fig. 3) into the steering gear housing 1 mechanism (see Fig. 2), remove the distributor;
- - disconnect cover 9 of the distributor assembly with input shaft 18 from the body 6 of the distributor assembly with spool 26 and bushing 12, first marking the position of the groove on the bushing 12, into which the nut flange 3 is punched, relative to the input shaft 18;
- - knock out the pin 19 from the input shaft 18 and clean the circular grooves of the shaft to the torsion bar;
- — by turning the screw 2 (see Fig. 4) move the nut-rail to one of the extreme positions;
- - unscrew the bolts and remove the side covers 15 to 19, remove the liners 12 and the gear sector 8 from the body;
- - unscrew the bolts and remove the cover 10, remove the screw 2 with the nut-rail 4 from the body.
With an external inspection, check the condition of the teeth of the rack nut and sector, the running tracks of the screw and rack nut, the condition of the bearings, balls and their guides.
The presence of small pockmarks (pitting) on the teeth of the sector and the rack nut, on the balls or on the treadmills of the screw, rack nut and rolling bearings indicates the beginning of wear on these parts.
In this case, it is better to replace the parts, as wear will progress.
When replacing worn parts, keep in mind that the replacement of the screw, rack nut and balls can only be done as a complete set.
Check the condition of the threads on the input shaft, the threads and splines of the spool sleeve, the splines of the screw and the plain bearings, which should not show signs of burrs.
There should also be no gap in the connection between the torsion bar and the screw.
Only the crankcase, side and bottom covers are subject to restoration in the steering mechanism when the seats for bearings are worn by installing repair bushings.
Other parts of the steering mechanism must be replaced if they are visible damage and wear.
The steering gear case, made of ductile iron, is subject to restoration if the diameter of the hole for the needle bearings of the gear sector of the steering sector of the steering gear is more than 55.05 mm by installing a repair sleeve (Fig. 5, a).
For this, the crankcase is installed on the faceplate of the lathe with a plane under the side cover, bore a hole for the repair sleeve up to 60 +0.06 mm and a socket for the shoulder of the repair sleeve up to a diameter of 64 +0.1 mm to a depth of 14 mm from the end of the neck.
Then, the bushing is pressed into the bored hole until it stops against the collar, providing an interference in the range of 0.05 - 0.075 mm, and the hole in the bushing is bored to a nominal diameter of 55 + 0.013 mm.
When the hole for the outer ring of the screw bearing is worn out to a diameter of more than 72.04 mm, it is restored by placing a repair sleeve (Fig. 5, b).
To do this, the hole is bored to a diameter of 76 + 0.06 mm, without violating the size of 203 + 0.2 mm from the end of the crankcase from the side of the bottom cover to the end of the bore of the hole.
The repair sleeve is pressed in until it stops with an interference in the range of 0.05 - 0.075 mm and a hole is bored in it to a nominal diameter of 72 + 0.02 mm.
The axes of the holes for the ring of the upper bearing of the steering screw and for the needle bearings of the gear sector must be mutually perpendicular with an accuracy of 0.03 mm per 100 mm.
The surfaces of the holes for the ring of the upper bearing of the rudder screw and for the bottom cover must be concentric, the allowable runout is 0.02 mm.
The crankcase side cover, made of malleable cast iron KCh 37 - 12, is subject to restoration if the thread for the adjusting screw is damaged and is rejected in case of breaks, cracks and wear of the seating surfaces.
If the M12 x 1.25 thread for the adjusting screw is damaged, the cover is restored by placing a screw driver, for which a hole with a damaged thread is drilled up to Ø 13.7 + 0.2 mm, the M16 thread is cut with a tap and the screw screw is screwed in.
Then, a hole Ø 2 mm is drilled to a depth of 6 mm at the threaded connection of the screw driver and the cover, a pin is pressed flush into the hole and the M12 x 1.25 thread in the screw driver is calibrated.
The lower crankcase cover, made of malleable cast iron KCh 37-12, is subject to restoration only when the hole for the outer ring of the bearing is worn out. In case of other defects of the cover, it is rejected.
A worn hole for the outer ring of a bearing more than 72.04 mm is restored by setting a repair sleeve.
The cover is installed with a seat neck on a lathe and a hole is bored to a diameter of 76 + 0.06 mm to a depth of 16 mm.
Then, a bushing with an inner diameter of 70 mm and a height of 16 mm is pressed into the bored hole, the hole is bored in it to a diameter of 72.2 mm and a chamfer of 1 x 45 ° is removed.
The steering mechanism is assembled in the reverse order of disassembly. Particular attention is paid to the installation of bearings and seals. These works are performed using special mandrels.
Steering mechanism assembly
The assembly sequence is as follows:
- — adjust the tightness in the bearings 13 (see Fig. 2) using shims 14. The moment required to turn the input shaft 18 in the cover should be within no more than 0.58 N m;
- —adjust the preload in bearings 4 and 11 using nut 3. The moment for turning sleeve 12 in the bearings should be within 0.02—0.04 Nm.
In this case, the body 6 with the spool must, under its own weight, move relative to the sleeve 12 in the radial direction by the amount of the gap between the sleeve 12 and the spool.
After adjusting, screw the collar of the nut 3 into the groove of the sleeve:
- - connect the sleeve 12 by thread with the input shaft 18 according to the marks made during disassembly. The splines on the sleeve must match the internal splines of the input shaft 18;
- — install screw 2 (see Fig. 4) with a nut-rail and bearings in housing 3. Use shims 9 to adjust the preload in the bearings.
The torque required to turn the screw 2 until the rail nut stops in the body 3 should be within 0.9—1.5 Nm.
Repeat the operation of determining the torque several times with a preliminary turn of the screw in the nut-rail (in the range of one turn);
- - set the nut-rail by turning the screw to the middle position;
- — install the sector with thrust rings 18 into body 3 so that the middle tooth of the sector falls into the middle cavity of the rail nut;
- - install liners 12 on the sector shaft on both sides. The risks on the ends of the bushings should be on the side opposite to the rail nut;
- - adjust the engagement of the nut-rail with the sector (see subsection "Adjusting the steering mechanism") so that the moment required to turn the screw (without distributor) in the middle position is within 2.9-3.9 Nm;
- - install the distributor in the steering gear housing according to the marks made during disassembly. In this case, the circular grooves in the torsion bar 20 (see Fig. 2) and on the input shaft 18 must match;
- - install the pin 19 and lock it by punching into the end of the input shaft 18. The pin should go into the hole with a slight interference.
When replacing parts of the distributor or the steering gear housing (except for the cover 22 of the stuffing box and the cuff 15), neoafter assembly, it is necessary to set the spool to the neutral position, for which:
- - install the steering gear on a stand equipped with a pump and a pressure gauge;
- - stop the sector shaft and plug the channels "K" and "G" with plugs to connect with the cylinder cavities; connect channel “B” to the pump, and channel “A” to the drain;
- —when the pump is running, by turning the input shaft 18, find the position at which the pressure in the system will be minimal; screw the bolt into the radial hole of the input shaft 18 and lock the torsion bar against the shaft.
When the torsion bar is locked, the spool must clearly return to the neutral position when the moment is removed from the input shaft 18;
- - if the circular grooves on the torsion bar and the shaft do not match, drill a hole to a larger diameter and install a new pin 19.
The torque required to turn the steering gear screw assembly with the distributor in the middle position of the rack nut should be within 2.7-4.1 Nm.
Dismantling the steering mechanism (Fig. 6) is similar to the steering mechanism (Fig. 4), only before removing sector 7 with liners 8, 15 from housing 4, you must first disconnect the bypass tube and pressure limiting valve 13 in order to prevent damage to it.
The assembly of the steering gear (Fig. 6) is similar to the steering gear (Fig. 4), only before installing the distributor in the steering housing:
- - fix the side covers 10 and 16, then install the pressure limiting valve 13 and the bypass pipe connecting the channel 6 for supplying oil to the distributor 5 and the annular bore 14 of the pressure limiting valve 13.
Installing the steering mechanism on the car
Installation order is as follows:
- - fix the steering gear on the frame bracket;
- - by turning the input shaft 18 (fig. 2) align the mark on the end of the sector shaft with the mark on the bipod, put the bipod on the splines of the sector shaft and secure it;
- - connect the yoke of the propeller shaft of the steering column to the input shaft 18, having previously installed the key, and wrap the coupling bolt into the yoke;
- - connect the hoses to the distributor and fill the system with oil.