The gearbox assembly is carried out in three stages: assembly of the drive shaft and drive shaft bearing cover, intermediate and driven shafts, gearbox top cover, remote gear shift mechanism, oil pump, general assembly of the gearbox and testing

The drive shaft and the drive shaft bearing cover are assembled in the following sequence:

MAZ gearbox

  • - install the drive shaft, (see Fig. 1) with a ring gear on the stand and press the rear ball bearing onto the shaft neck until it stops, having previously installed the retaining ring in the groove of the outer race;
  • - screw a ring nut onto the threaded neck of the shaft and tighten it to failure. The edge of the nut is punched into the groove of the shaft;
  • - install cover 3 of the drive shaft bearing with the socket under the oil seal up and press the oil seal into the socket until it stops, having previously lubricated the outer surface of the oil seal with nitro enamel.

The intermediate and driven shafts are wiped before assembly, and the mating surfaces are lubricated with oil.

The intermediate shaft is assembled in the following order:

  • - install the shaft 17 (see Fig. 1) with a ring gear on the hydraulic press table, press the key into the groove of the shaft and press the gear 19 of the second gear onto the shaft until it stops into the ring gear of the shaft. Gear hub 19 must face away from the ring gear;
  • - put on the shaft the spacer sleeve of the gears of the second and third gears, press the segment key into the groove of the shaft and press the gear 21 of the third gear to the stop with a short hub towards the spacer;
  • - press the key into the groove of the shaft and press the gear 22 of the fifth gear to the stop with a short hub towards the gear 21 of the third gear;
  • - press the key into the groove of the shaft and press the gear 23 of the power take-off with a long hub from the gear 22 of the fifth gear to the stop;
  • - press the key into the groove of the shaft and press the gear 24 to the stop with the long hub towards the gear 23 of the power take-off;
  • - install the front thrust ring into the shaft groove, press the front roller bearing against the stop on the shaft and install the bearing thrust ring into the shaft groove.

The driven shaft is assembled in the following sequence:

  • - install shaft 14 (see Fig. 1) with the threaded end down;
  • - install a thrust washer on the shaft until it stops at the end of the splined surface and gear 11 of the second gear with a ring gear from the thrust washer. The gear on the shaft should rotate easily without jamming;
  • - the keys are pressed into the grooves of the shaft and the spacer sleeve of the gears of the second and third gears is pressed onto the shaft until it stops with the large end towards the second gear of the second gear;
  • - install on the splines of the spacer sleeve the synchronizer 10 of the second and third gears, complete with a carriage with a short hub to the gear 11 of the second gear;
  • - press the bushing of gear 9 of the third gear onto the shaft until it stops into the spacer bushing, while aligning the cutout in the bushing with the key of the spacer bushing, and install gear 9 on the bushing with a spur ring in the direction of the synchronizer 10. The gear on the shaft should rotate easily without jamming ;
  • - check the longitudinal movement of the holder of the conical rings of the synchronizer 10, which should be within 3-5 mm. The clutch of the teeth of the synchronizer carriage with the teeth of the gear should be easy, without jamming;
  • - press the bushing of gear 8 of the fifth gear to the stop on the shaft with a collar towards gear 9 of the third gear and, at the same time, aligning the pin of the bushing with the groove of the shaft, install gear 8 on the bushing with a spur ring away from the shoulder of the bushing.

The gear should rotate easily on the shaft, without jamming;

  • - install the thrust washer of gear 8 of the fifth gear, rotating it until the protrusions of the washer align with the splines of the shaft, and press in the locking key.

The gap between the fifth gear bushing and the thrust washer should be within 0.02-0.1 mm, which is ensured by selecting the thickness of the thrust washer before installing the fifth gear.

Thrust washers are made in three thicknesses: 7-0.58, 7.15-0.58 and 7.3-0.58mm;

  • - install the synchronizer 5 of the fourth and fifth gears on the splines of the driven shaft 14 with a spur rim of the carriage of a smaller diameter towards the fifth gear;
  • - press the front roller bearing onto the front journal of the shaft until it stops and install the thrust spring ring into the groove on the front journal;
  • - the oil seal is pressed into the hole of the cover 15 of the driven shaft flush with the inner end of the hole. Before pressing the stuffing box, the seating surface of the hole in the cover is lubricated with nitro enamel.

The upper cover of the gearbox is assembled in such a sequence Values:

  • - insert the spring 19 and the locking ball 18 into the socket of the cover 1, insert the stem 21 into the holes of the cover while simultaneously installing the head 11 and the reverse fork 3 on the stem.

When installing the stem, a mandrel is used (Fig. 3). Combine the threaded holes of the head and fork with the holes in the stem and fasten them with a locking screw, which is countered with a cotter pin;

MAZ gearbox cover

  • - install the stem 5 of the third and fourth shift fork into the cover 1 (Fig. 2) and at the same time install the fork 8 on the stem.

Combine the threaded hole in the fork with the hole in the stem and fix the fork with a locking screw 9, which is countered with a splint wire;

  • - inserted into the channels of the cover under the stem 21 of the reverse fork and under the stem 5 of the shift fork of the third and fourth, two balls each 7 of the lock of the gear shift rod;
  • - set rods 21 and 5 to neutral position;
  • - insert the pin of the lock of the rods into the hole of the rod, which should move freely in the hole and the assembled rod with the head 1 installed on it, the fork 4 for switching the first second gear is inserted into the cover.

Combine the threaded holes of the head and fork with the holes in the rods and install a locking screw in them, which is countered with a splint wire;

  • - insert plugs 10 into the holes of the cover for the rods.
  • - Plugs are installed on nitro enamel;
  • - install the leash 15 for turning on the reverse gear on the cover and fix it with the axis 14, on the threaded end of which a nut is screwed
  • - insert the fuse spring into the glass 13 and screw the glass into the lid;
  • - screw the oil filler plug 2 and the breather assembly into the cover 1

The remote gear shift mechanism is assembled in the following sequence:

  • - insert pin 33 (see Fig. 1) into the bushing, install a spring on the pin head into the bushing, and then install the sub-assembled assembly with the bushing into the crankcase socket 30, aligning the hole in the bushing with the threaded hole in the crankcase, and screw in the locking bolt with spring washer;
  • - screw oil filler and oil drain plugs into the crankcase 30;
  • - insert a segmented key into the groove of the shaft 34, put on the shaft the intermediate gearshift lever 29, having previously aligned the groove in the lever with the key and the threaded hole with the hole in the shaft, screw in the set screw and lock it with splint wire;
  • - install the assembled shaft 34 into the crankcase 30 from the hatch side of the crankcase cover;

Shift Fork Driver

  • - insert a key into the groove of the free end of the shaft and put the gearshift lever 6 on its end, aligning the threaded hole in the lever with the hole in the shaft, screw in the set screw and lock it with a splint wire like the intermediate lever 29;
  • - put on the ball surface of the intermediate lever 29 the head of the rod 28, insert the sealing ring of the rod 28 into the crankcase groove and insert the rod 28 into the crankcase from the side of the sealing ring with a recess for the bolt of the rod head from the intermediate lever 29, while putting the head on the rod so so that the threaded hole in it is located from the hatch;
  • - align the hole in the head with the notch on the stem 28 and screw in the head bolt with the lock washer;
  • - lubricate both sides of the crankcase cover gasket with sealing paste, install it on the crankcase hatch, aligning the holes for the bolts, put the mechanism crankcase cover on the gasket and screw the bolts with spring washers into the aligned holes.

The oil pump is assembled in the following sequence:

  • - a segment key is pressed into the groove of the pinion shaft and the shaft with the key is pressed into the pinion, keeping the size (25.5 ± 0.5) mm from the end of the gear to the end of the shaft from the side of the shank;
  • - they put the driven gear assembly with a bronze bushing on the axle and insert the roller assembly with the drive gear into the bushing at the base;
  • - install the gasket of the pump housing on the base, after degreasing it with white spirit and lubricating it on both sides with a sealing paste;
  • - install the pump housing assembly with gears on the base, aligning the holes of the housing, gasket and base, and screw in the bolts with spring washers;
  • - check the ease of rotation of the gears, which should rotate by hand easily and without jamming;
  • - insert a ball, a spring into the socket of the pump housing and screw the plug of the bypass valve to failure;
  • - cotter bolts and valve plugwire with a diameter of 1.2 mm;
  • - test the assembled pump on the stand in Dp - 11 oil at a temperature of (50 ± 5) ° С at a drive shaft speed of 1100 min for at least 3 min:

When testing, the oil pressure at the outlet should be in the range of 0.7-0.12 MPa (0.7-1.2 kgf / cm²) and the productivity should be at least 7 l / min at a back pressure of 0.07-0, 12 MPa (0.7-1.2 kgf / cm²). Oil leakage through the connections is not allowed.

The general assembly of the gearbox is performed in the following sequence:

  • - install the intake grid with the gasket assembly into the lower hatch of the crankcase 18 (see Fig. 1) of the gearbox, place the intake cover 20 with the magnet assembly on the grid and screw the bolts with spring washers into the aligned holes, tightening them evenly;
  • - install gaskets and covers on the side hatches of the crankcase and screw the bolts into the aligned holes. Manhole cover gaskets and threaded bolt holes are lubricated with sealing paste before installation;
  • - purge the oil channels and the internal cavity of the box crankcase with compressed air, screw oil drain plugs and an oil level control plug into the crankcase, having previously lubricated the threaded holes with sealing paste;
  • - install the intermediate shaft 17 assembly in the gearbox housing with the bearing in the front seat, install the retaining ring in the groove of the outer race of the ball bearing, press the rear ball bearing onto the end of the intermediate shaft and into the crankcase hole at the same time, install the thrust washer on the end of the intermediate shaft , screw the bolts into the aligned holes, tightening them to failure;
  • - assemble a block of 27 reverse gears with roller bearings and an intermediate sleeve, having previously lubricated the roller bearings with TsIATIM-201 grease;
  • - install the reverse gear block in the gearbox crankcase 18 with a small ring gear to the rear end of the crankcase, press the axis 26 of the gear block into the holes of the crankcase of nominal or repair size (see table) so that the flat on the end of the axle faces rear intermediate shaft bearing;
  • - install the cover of the rear bearing of the intermediate shaft on the end of the crankcase of the box with a protrusion to the flat on the axis of the gear block and screw the bolts with spring washers into the aligned holes, tightening them evenly;
  • - check the rotation of the reverse gear block and the intermediate shaft by supplying compressed air at a pressure of 0.5-0.7 MPa (5-7 kgf / cm²) to the teeth of the gear block. Knocks, rattles and uneven noise are not allowed;
  • - install the gear 12 of the first gear and reverse gear on the splines of the driven shaft 14 and check the ease of its movement along the splines, remove the gear from the shaft and place it in the crankcase 18 of the gearbox, blow the driven shaft assembly with compressed air and smoothly install it in crankcase, while simultaneously installing the first gear and reverse gears on it;

Assembly of MAZ gearbox (mating table)

  • - purge the channels of the drive shaft with compressed air and install the drive shaft 2 assembly with the bearing into the hole in the crankcase 18, aligning the oil drain tube with the hole in the driven shaft;
  • install the retaining ring in the groove of the outer race of the rear ball bearing of the driven shaft 14 and press the bearing onto the rear end of the driven shaft into the hole in the crankcase of the box 18 at the same time;
  • check the ease of rotation of the shafts by hand. The shafts should rotate easily, without jamming, in the position of the synchronizers and gear 12 of the first gear and reverse;
  • press the drive gear of the speedometer drive onto the rear end of the driven shaft 14, install the gasket and cover 15 of the rear bearing of the driven shaft, having previously lubricated the working surface of the stuffing box in the cover with TsIATIM-201 grease, screwing a bolt with spring washers into the aligned holes and tighten them evenly to failure;
  • the flange 16 of the driveshaft fastening is pressed in until it stops, a Belleville washer is put on the splined end of the driven shaft, the nut is screwed on and tightened until the slot of the nut is aligned with the hole in the shaft and the cotter pin is inserted.
  • lubricate the helical groove and the working surface of the stuffing box in the cover 3 of the input shaft bearing 2 with TsIATIM-201 grease, the sealing gasket of the cover on both sides and the threaded holes in the crankcase for the cover fastening bolts - with sealing paste “Sealant”;
  • put a gasket on the flange of the cover, aligning the holes for the bolts, install the cover 3 on the drive shaft 2, aligning the oil outlet channel in the cover with the throttle sleeve in the crankcase 18 of the gearbox, screw the bolts into the aligned holes, tightening them to failure, after placing them under they are flat washers, and lock the bolts in pairs with a splint wire with a diameter of 1.2 mm;
  • lubrication seal the oil pump seal 25 on both sides and the threaded holes in the crankcase 18 of the box for the oil pump mounting bolts with sealing paste “Sealant”;
  • lay a gasket on the base of the oil pump 25, aligning the holes for the bolts, install the pump assembly on the crankcase 18 of the gearbox, aligning the position of the protrusion of the drive pinion shaft shank with the groove in the intermediate shaft 17 and pointing the cut off part of the base towards the cover 3 of the drive shaft bearing , and screw bolts with flat washers placed into the aligned holes, which are locked in pairs;
  • check the rotation of the shafts of the box by hand, which should rotate easily, without jamming;
  • install the upper and lower covers on the hatches of the crankcase 4 of the clutch and fix them with bolts with enclosed spring washers;
  • lubricate the threaded holes in the crankcase 18 of the gearbox for the bolts of the clutch crankcase 4 with sealing paste “Sealant”;
  • install the assembled clutch housing 4 on the end of the gearbox, screw bolts with spring washers in the aligned holes of the clutch housing and gearbox and lock them in pairs with cotter pin-wire with a diameter of 1.6 mm;
  • insert the shaft of the clutch release fork into the bushings of the clutch housing 4 so that the splined end of the shaft is on the left, if you look at the gearbox from the side of the cardan shaft flange, check the ease of rotation of the shaft by hand, insert the key into the groove of the shaft, pull the shaft out of one bushing, install the clutch release fork on it with the treated platforms forward, screw the coupling bolt with washers into the hole of the fork, set the fork symmetrically to the pipe of the cap 3 of the input shaft bearing and tighten the coupling bolt completely;
  • the bearing is pressed onto the neck of the clutch 1 of the clutch release until it stops. After pressing on, the inner race and the outer race of the bearing must rotate freely by hand;
  • install the clutch 1 assembly on the cover 3 of the input shaft bearing, check the ease of movement of the clutch along the input shaft cover, connect the clutch with springs by inserting their ends into the holes of the clutch and fork;
  • fix the clutch release clutch lubrication hose by screwing its ends into the clutch and clutch housing;
  • they are screwed into the tip of the hose fixed on the clutch housing and into the holes for lubricating the bearing journals of the clutch release shaft, angled oilers;
  • set the synchronizers 5, 10, the gear 12 of the first gear and the reverse gear to the neutral position, put the gasket on the mating plane of the crankcase 18 of the gearbox with the top cover 13, aligning the holes for the bolts, install the top cover 13 assembly on the gasket, aligning the forks gears with grooves of synchronizers 5 and 10 and gears 12 of the first gear and reverse gear, screw the bolts into the aligned holes and tighten them evenly
  • install the gasket of the remote shift mechanism on the studs of the top cover, put the remote shift mechanism assembly on the gasket so that it is directed towards the splined end of the clutch release shaft, and the gear lever enters the groove of the gear shift rod head, put spring washers on the studs, screw on the nuts and tighten them to failure;
  • insert the speedometer drive gear into the cover 15 of the rear bearing of the driven shaft 14, install the cover of the replaceable gears with the shaft of the driven spur gear and fix it with bolts;
  • lubricate the clutch release clutch and the clutch release shaft bushings through the grease fittings with universal refractory grease.
  • The assembled gearbox must meet the following requirements before being tested on the stand:
  • the shafts of the gearbox, when the drive shaft is rotated by hand, should rotate freely, without sticking, both with the gear lever in neutral and with the first gear and reverse gear disengaged;
  • Shifting all gears should be effortless. Rod clamps must clearly fix the rods in the position of the gear engaged and disengaged. Simultaneous inclusion of two gears is not allowed;
  • when the clutch release drive shaft is rotated by hand, the clutch release clutch should move freely, without jamming, along the guide cover of the input shaft bearing until the ends of the clutch and cover come into contact.

When testing a repaired gearbox on the stand, it is allowed to use regenerated diesel oil dp - 11, heated to a temperature of 65 ° C, as a lubricant, poured into the gearbox and into the remote control mechanism.

Gearboxes are tested in all gears both without load and under load, creating 2 braking torque on the output shaft.

The operation of the gearbox on the stand in any gear engaged should occur without sharp noises and knocks. Noise level they are heard by ear, compared with the reference gearbox.

Shifting gears should occur without much effort and jamming. With the neutral position of the gear lever and at maximum speed of the input shaft.

Slight rotation of the driven shaft is allowed, eliminated by a torque of no more than 15 Nm (1.5 kg/cm) applied to the flange.

Oil leakage through the gearbox connections is not allowed. There may be slight leakage of oil through the seals and breather, but without dripping.

The temperature of the oil in the gearbox housing during testing should not exceed 85°C.

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