Only the crankcase, input shaft bearing cap, intermediate shaft, reverse gear block, third gear of the output shaft, oil pump housing and base are subject to repair in the gearbox
Other parts of the gearbox must be replaced if they are damaged or worn.
The gearbox housing, cast from special cast iron, must be restored if the holes for the bearings of the drive, driven and intermediate shafts, the holes for the axis of the reverse gear block bearings, the holes for the dowel pins and the threaded holes are worn out.
If the holes for the bearings of the input shaft are worn out up to a diameter of more than 150.08 mm and the driven shaft up to a diameter of more than 140.08 mm, they are restored by setting bushings.
To do this, the hole for the drive shaft bearing is bored to Ø 155 + 0.08 mm and at the same time the undercut Ø158 + 0.3 mm is bored to a depth of 2.5 + 0.2 mm under the collar of the repair sleeve.
Then, the crankcase is reinstalled and a hole is bored for the repair sleeve of the driven shaft bearing to Ø 145 + 0.08 mm and at the same time the recess Ø 148 + 0.3 mm is bored to a depth of 2.5 + 0.2 mm under the collar of the repair sleeve
Repair bushings are pressed into the bored holes (Fig. 1) until they stop against the collar, providing an interference in the range of 0.08-0.15 mm, and the holes in the bushings are bored into a line.
The hole for the drive shaft bearing is bored to Ø 150 + 0.04 mm and the hole for the driven shaft bearing - up to Ø 140 + 0.1 mm.
The holes for the front bearing of the intermediate shaft, worn to a diameter of more than 90.07 mm, and the holes for the rear bearing of the intermediate shaft, worn to a diameter of more than 120.07 mm, are also restored by setting bushings.
The hole for the front bearing bush is bored to Ø 959.07 mm and at the same time the undercut Ø 98 + 0.03 mm is bored to a depth of 2.5 + 0.5 mm under the collar of the bush.
Then, a hole for the repair sleeve of the rear bearing is bored to Ø 125 + 0.08 mm and at the same time the undercut is bored to Ø 128 + 0.3 mm to a depth of 2.5 + 0.2 mm under the collar of the sleeve.
The repair bushings are pressed into the holes until they stop against the collar, ensuring an interference fit in the range of 0.08-0.15 mm, and the holes in the bushings are bored to the nominal size in a line.
The hole for the front bearing is bored to Ø 90 + 0.035 mm, and for the rear bearing - up to Ø 120 + 0.035 mm.
If the holes for the axis of the reverse gear block are worn to a diameter of more than 26.05 mm under the front end of the axle and to a diameter of more than 32.05 mm under the rear end of the axle, they are restored by reaming to one of the repair sizes given in the table, or restored bushings.
When restoring holes by setting bushings, drill holes for the front end of the axle up to Ø 29.8 mm. under the rear end of the axle up to Ø 35.8 mm.
Then, the holes are expanded to diameters of 30 + 0.045 mm and 36 + 0.05 mm, respectively. In holes
repair bushings are pressed in, which have the following main dimensions: under the front end of the axle, outer Ø 30 + 0.095 mm and length 26 mm, under the rear end of the axle - outer Ø 36 mm and length 30 mm.
After pressing in, the bushings are welded in two diametrically opposite places, the holes in the bushings are drilled and reamed to the nominal diameter (see table).
Holes for locating pins worn to a size of more than 14.03 mm are reamed to a repair size of 14.2 + 0.013 mm.
Damaged threaded holes are repaired with epoxy adhesive screws.
So, if the threaded hole M16 cl. 2 it is drilled to Ø 17.1 + 0.2 mm, the M20 thread is cut with a tap and the screw driver is screwed flush with the plane of the base metal.
The requirements for the relative position of the surfaces of the repaired gearbox housing should be as follows:
- - non-parallelism of the axes of the surfaces of the holes for ball bearings of the drive and driven shafts relative to the plane of the connector with the top cover is allowed no more than 0.12 mm;
- - non-parallelism of the axis of the surfaces of the holes for the ball bearings of the drive and driven shafts relative to the axis of the surfaces of the holes for the intermediate shaft bearings should not exceed 0.08 mm;
- - non-parallelism of the axis of the surfaces of the holes for the axis of the bearings of the reverse gear unit relative to the axis of the surfaces of the holes for the intermediate shaft bearings is allowed no more than 0.03 mm over a length of 100 mm;
- - non-perpendicularity of the ends of the crankcase from the side of the holes for the bearings relative to the axis of the surfaces of the holes for the bearings of the drive and driven shafts should not exceed embroider 0.07 mm on a length of 100 mm;
- - mutual runout of the surfaces of the holes for the axis of the bearings of the reverse gear unit should not exceed 0.05 mm;
- - deviation of the axes of the surfaces of the holes for the bearings of the drive, driven and intermediate shafts from the position in one plane should not exceed 0.08 mm;
- - deviation of the axes of the surfaces of the holes for the bearings of the intermediate shaft and the holes for the axis of the bearings of the reverse gear units is allowed no more than 0.03 mm over a length of 100 mm;
- - the distance from the axis of the holes for the axis of the reverse gear block to the axis of the holes for the intermediate shaft bearings should be (89.25 ± 0.042) mm and to the axis of the holes for the bearings of the drive and driven shafts - (182.75 ± 0.042) mm .
- - the distance between the axes of the holes for the bearings of the intermediate shaft and for the bearings of the drive and driven shafts should be (165.75 ± 0.042) mm;
- the distance from the axis of the mounting holes to the axis of the holes for the bearings of the drive and driven shafts should be (136±0.15) mm;
- - the distance between the axes of the mounting holes should be (433±0.05) mm;
- - the distance from the plane of the gearbox housing connector with the top cover to the axis of the holes for the bearings of the drive and driven shafts should be (109.5 ± 0.2) mm.
The drive shaft bearing cap, made of malleable cast iron KCh 35-10, is subject to restoration in case of the following defects: breaks and cracks in the pipe, wear of the hole with an oil drain groove, hole for the stuffing box, holes for the bolts of fastening to the gearbox housing, end surface flange for the retaining ring of the drive shaft bearing.
In case of breaks and cracks on the cover pipe, cut off the damaged pipe, maintaining a size of 60 mm to the surface of the flange of the box mating with the crankcase, bore the hole to 55 + 0.06 mm through the repair sleeve (Fig. 2) and grind the chamfer 5 x 45 °.
Then, the repair sleeve 1 is pressed into the bored hole under the clutch release clutch, it is welded from the outside with a continuous seam, preventing overheating of the base metal, and installed on the faceplate.
The end of the pipe is cut to the length of the entire cover, equal to 170 mm, the outer surface is turned to Ø 55.5-0.1 mm and the chamfer is 1.5 x 30 °, the hole is bored, Ø 44 mm to a length of 90 mm and 1 x 45° chamfer.
After that, install the cover with the coupling surface into the chuck with elongated jaws, cut the end of the pipe flush with the base metal, grind the hole for the oil drain groove to 42 + 0.34, bore the chamfer in this hole at an angle of 30 ° to Ø 50 mm and cut a spiral tap with a special tap oil drain groove with a pitch of 4 mm, a width of 3 mm and a depth of 1.0 mm.
The number of turns must not be less than four. Finally, the neck for the clutch release up to Ø 55 mm is processed in special fungal centers on a cylindrical grinder.
A hole with an oil-cut thread, worn to a diameter of more than 42.70 mm, is bored to Ø 46 + 0.05 mm for a length of 30 + 0.34 mm under the repair sleeve (see Fig. 2).
Then, the bushing is pressed into the bored hole until it stops into the ledge, the end face of the bushing is cut flush with the base metal, the hole is bored up to Ø 42 mm for oil cutting, the chamfer is bored in the hole at an angle of 30 ° to Ø 50 mm and the oil drain groove is cut.
When the hole for the stuffing box is worn out to a size of more than 64.12 mm, it is restored by setting the sleeve.
To do this, the hole is bored to Ø 68 + 0.06 mm at a length of 24.5 + 0.34 mm, bushing 3 is pressed into the bored hole (see Fig. 2) until it stops, aligning the holes in the bushing with the oil channel in cover, cut the end of the sleeve flush with the base metal, bore the hole in the sleeve for the stuffing box to Ø 64 + 0.06 mm and bore the chamfer 1.5 x 30 °.
The hole for the stuffing box is bored in the reverse faceplate, based on the surface of the undercut for the outer race of the ball bearing.
The holes for the bolts of the cover to the gearbox housing, worn out to a diameter of more than 11.5 mm, are welded with a TsCh-4 electrode Ø 3 mm.
Then, the welded surface of the flange is cleaned flush with the base metal, six holes Ø 11 mm are drilled, and holes up to Ø 18 mm are countersinked from the side of the pipe.
When the end surface of the cover for the bearing lock ring is worn to a size of more than 3.05 mm, the worn end is cut “as clean” to Ø 160 mm, a chamfer is bored 0.3x45 °, the flange end is cut Ø 200-0.047 mm, ensuring the depth of the undercut under the retaining ring (2.85 ± 0.1) mm, and cut the end of the undercut under the outer race of the ball bearing up to Ø 150 mm, providing a size of (7.6 ± 0.1) mm from the end of the undercut to the end of the flange.
When repairing the drive shaft bearing cover, the following requirements must be met:
- - when centered and covers on the surface under the outer race of a ball bearing with an emphasis on the end of the flange, the runout of the outer surface of the flange should not be more than 0.04 mm;
- - runout of the surface of the hole for the stuffing box should not exceed 0.08 mm;
- - the runout of the surface of the hole with oil cutting is allowed no more than 0.2 mm;
- - the runout of the surface under the clutch release clutch should not be more than 0.2 mm;
- - mutual non-parallelism of the ends of the flange and the undercut for the bearing is allowed no more than 0.05 mm.
The intermediate shaft is made of 15KhGNTA steel and cemented to a layer depth on the teeth of 0.9-1.2 mm, followed by heat treatment to a tooth surface hardness of HRC 58-64.
The hardness of all ground surfaces must be at least HGC 50.
The intermediate shaft is restored with the following defects: broken teeth, chipping of the working surface of the teeth, wear of the teeth at the ends, teeth in thickness, necks for bearings and necks for shaft gears.
In case of tooth breakage, chipping of the working surface of the teeth, wear of the teeth at the ends to a size of less than 62.0 mm, and when the teeth are worn in thickness to a size of less than 7.65 mm, a repair crown is installed.
To do this, a 59 mm neck and a ring gear are annealed on a high-frequency installation, heating them to a temperature of 780-800 ° C, and placed in a box with dry sand.
Then the shaft is corrected until the runout in the fixture is eliminated on a hydraulic press.
The runout of the ground surfaces relative to the journals for bearings should not exceed 0.025 mm.
After that, the center holes of the shaft are fixed on a screw-cutting lathe, the shaft is installed in the center of the machine, the ring gear is turned to Ø 59 mm, the neck Ø 59 mm to a diameter of 46.5-0.12 mm at a length of 138.7-0 .16 mm for grinding and chamfering 5 x 45°.
Then, the neck for the repair crown is ground up to Ø 46 mm for a length of 68-0.2 mm (Fig. 3, a) and the neck for the sleeve up to Ø 45.9 + 0.057 mm for a length of 70.7 mm.
Install the shaft on the stand of the hydraulic press and press the ring gear (Fig. 3, b) until it stops against the end, ensuring an interference fit in the range of 0.02-0.05 mm.
The ring gear is heat treated before being pressed onto the shaft and is made of the same steel as the shaft.
Then, the toothed (Fig. 3, c) crown is welded to the shaft with a circular seam on both sides (without filling the keyway and tooth cavities) with a UONI-13/55 Ø 4 mm electrode in a fixture installed in a bath of water.
After that, the shaft is corrected until the runout is eliminated, the welding seam is turned from the side of the keyway, deepening it by 0.5 mm from the surface of the neck, the end of the crown is cut “as clean” and the welding seam is turned from the opposite side of the crown.
The sleeve is pressed onto the shaft until it stops.
Into the crown, providing an interference in the range of 0.02-0.05 mm, cut the end of the sleeve flush with the shaft, providing a size of 133.5-0.15 mm to the end of the crown and dulling the edges of the sleeve with a radius of 0.5 mm.
The worn journal for the front bearing is restored by vibro-arc surfacing, and the journals for the shaft gears are chrome-plated.
The reverse gear block is made of 15KhGNTA steel and cemented to a layer depth of 0.9-1.2 mm on the teeth, followed by heat treatment to a tooth surface hardness of HRC 58-64.
The gear block is restored when the teeth of the small crown are broken or the working surface of the teeth of the small crown is chipped, when the small crown is worn along the ends and thickness.
A gear block is rejected when the teeth of the large ring break or the working surface of the teeth is chipped, when the teeth of the large ring are worn in thickness to a size of less than 6.25 mm and when the hole for roller bearings is worn to a size of more than 52.10 mm.
In case of breakage of the teeth of the small crown, wear at the ends to a size of less than 25.0 mm and wear in thickness to a size of less than 7.60 mm, a ring gear is installed. To do this, the defective crown is annealed, heated to a temperature of 780-800 ° C, and placed in a box with dry sand.
Then, the ring gear is turned to Ø 72-0.12 mm at a length of 35-0.12 mm, a chamfer is turned 5 x 45 ° and the neck is ground to Ø 72 mm.
The ring gear is pressed (Fig. 3) onto the machined neck of the gear block flush with the end of the block, ensuring an interference fit in the range of 0.05-0.08 mm.
The gear block is installed in the fixture, immersed in a bath with a 4% solution of soda ash and the crown is welded with a circular seam on both sides with an electrode of the brand UONI-13/55 Ø4 mm.
During the welding process, some deformation of the roller bearing bore is possible. Therefore, the hole is ground to Ø 52 mm at the point of deformation on an internal grinding machine, with a grinding wheel E25SM2-S2K PP40 x 60 x 20.
The end of the gear block on the side of the small crown is ground to a size of 125-0.15 mm on a cylindrical grinding machine.
3rd gear driven shaft a is made of steel 15KhGNTA and case-hardened to a tooth depth of 0.9–1.2 mm, followed by heat treatment to a hardness of HRC58–64. Teeth core hardness HRC 30-45.
The gear is restored with the following defects: broken internal gear teeth or chipping of the working surface of the teeth, wear of the internal gear teeth at the ends with a size of less than 8.0 mm and wear of the internal gear teeth in thickness, with a backlash of more than 0.85 mm between the gear teeth and a mating reference piece measuring 138.366 + 0.152 mm, measured by balls Ø (7.938 ± 0.005) mm.
With these defects, the gear is restored by setting the ring gear (Fig. 4, a).
To do this, the gear is annealed in an electric furnace, heated to a temperature of 780-800 ° C, and cooled together with the furnace.
Then, the damaged ring gear and the conical part of the gear are cut flush with the end of the gear, the socket for the ring gear is bored (Fig. 4, b) to Ø 112 mm and Ø 151.24 + 0.040 mm to a depth of 9 + 0.1 mm and , providing a fillet with a radius of 1 mm, grind a chamfer on the surface Ø 112-0.1 mm at an angle of 45 ° to the surface of the gear hub.
The gear is processed in a faceplate on a screw-cutting lathe.
The ring gear (Fig. 4, c) is pressed into the bored gear seat and the beating of the conical surface of the ring is checked (which should not exceed 0.06 mm), based on the inner hole of the gear, the ring gear is welded to the gear with a circular solid electrode of the UONI- brand 13/55 Ø4mm and grind the deposited to a size of 25 + 0.52 mm from the end of the gear.
Then, the gear is hardened by heating it for 50 minutes to a temperature of 825˚—850°C, holding at this temperature for 15 minutes.
Then the gear is cooled in SU engine oil, subjected to tempering by heating for 70 minutes to a temperature of 170-200 ° C with holding at this temperature for 20 minutes, and cooled in air.
After hardening, the gear is cleaned of scale, the hole in the gear is ground to an increased Ø 78.20 + 0.03 mm in a special faceplate on an internal grinding machine, based on the pitch circle of the teeth of constant engagement.
The conical surface of the ring gear is ground, providing Ø 149 mm at a distance of 3.5 + 0.15 mm of the end of the gear hub from the side of the ring, and an angle of 7 ° 30'.
The runout of the conical surface relative to the surface of the hole in the gear should not exceed 0.05 mm.
The conical surface of the ring gear is checked with a cone gauge for paint. The mating surface with the taper gauge should not be less than 65%.
The ring gear is made of the same steel as the gear. The crown is cemented before being pressed into the gear. The parameters of the teeth of the crown must correspond to the working drawing of the gear.
The oil pump housing is restored when the sockets for the gears are worn out in diameter, the axis of the driven gear, the holes in the bushing for the oil pump shaft.
When gear sockets are worn out with a diameter of more than 43.10 mm and the end surface of the gear sockets is worn to a size of more than 16.0 mm, boring is carried out to an increased diameter, followed by setting gears with an increased outer diameter when assembling.
To do this, the bosses of the holes for the mounting bolts are trimmed to a size that ensures the same height of all the bosses. This size should not be less than 22 mm.
Then, the pump housing is installed with the ends of the machined bosses on the fixture, the end of the socket for the gears is machined “as clean”, the mating surface of the housing with the pump base is cut to the depth of the socket (16.5 ± 0.03) mm, and the sockets are bored for the driven and pinion up to Ø 45.5+0.05 mm.
The non-flatness of the mating surface of the housing with the pump base should be no more than 0.02 mm, and the non-parallelism of the end surface of the sockets for the gears should be no more than 0.05 mm over a length of 100 mm.
The surfaces for the axis of the driven gear and the driven gear, the surfaces of the sleeve for the roller and the drive gear must be concentric in pairs, the allowable runout is not more than 0.03 mm.
The body is rejected if the height of the bosses for the oil pump mounting bolts is less than 20.5 mm.
The worn axle of the driven gear up to a diameter of less than 13.95 mm is replaced with a new one. to do this, drill a hole Ø b mm in the pump housing on the opposite side of the axis until the drill stops against the axis.
The defective axle is pressed out of the housing, a new axle is pressed in and the hole in the housing is welded with a copper-steel electrode Ø 3 mm.
The axis of the driven gear after pressing should be (1 ± 0.5) mm from the mating surface of the housing with the pump base.
When the hole in the bushing for the oil pump drive gear shaft is worn out to a diameter of more than 14.06 mm, the bushing is replaced.
In order to press the bushing out of body, fix the tap M 16 in a bench vise and, by rotating the oil pump housing, screw the tap into the sleeve.
Then, with a light tapping of the hammer on the body, the sleeve is pressed out of the body. A new bushing is pressed into the housing with a 0.5 mm recess from the end surface of the socket for the drive gear.
The hole in the sleeve is reamed up to Ø 14+0.040
The difference in wall thickness of the sleeve is allowed no more than 0.3 mm. The distance between the axes of the holes for the axles and the gear shaft should be 34.42 + 0.04 mm and the non-perpendicularity of the axes of the holes of the surface of the mating surface of the housing with the pump base should be no more than 0.05 mm over a length of 100 mm.
The base of the oil pump is restored if there are scratches and scuffs on the end surface for the gears and if the hole in the bushing for the oil pump roller is worn out.
If there are scratches and scuffs, the end surface for the gears is ground “as clean” on a surface grinder, with a grinding wheel KCh40MZ-SM1K PP250x25x
The finished surface should be 0.5 mm higher than the rest of the base.
At a lower height, the base is rejected.
The surface of the gear is ground in a special device, while the surface of contact with the gearbox housing is taken as the base surface, since these surfaces must have a non-parallelism of more than 0.05 mm over a length of 100 mm, and the total surface to be machined must be flat with an accuracy not more than 0.02 mm.
When the hole in the bushing for the oil pump shaft is worn to a size of more than 14.06 mm, the bushing is pressed out and a new bushing is pressed in, sinking it into the base 0.5 mm from the mating surface with the pump housing.
Then, the hole in the bushing is bored and reamed to Ø 14 + 0.040 in a special faceplate on a lathe, based on the mounting surface of the interface with the gearbox housing Ø 90 mm.
The axes of these surfaces should be concentric, should not exceed 0.08 mm. The perpendicularity of the axis of the sleeve surface to the end surface for the gears should be no more than 0.05 mm over a length of 100 mm
