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Massey Ferguson 7720, 7726, 7480, 7495 Dyna VT transmission PTO

MF 7400-7700 Series Tractors Repair Operations

Disassembling the Dyna VT transmission power take-off

Lower the rear linkage. Drain the transmission oil. Remove the trailer linkage (depending on equipment). Mark and remove the PTO connector TR9.

Mark and remove the PTO connector TR10. Unscrew all attachment screws. Take the silicone out of the threaded bores and tighten 2 screws M12 Support the cover using a lifting tool and push it back using the two screws.

Take off the Massey Ferguson 7480, 7495 rear PTO transmission cover. Take care of the adjustment shims, which are used to adjust the bearing clearance.

Push back the clutch cover (3) using 2 disc screws M10. Remove the nozzle (29). Fit the compression tool and compress the clutch. Extract the locking half-rings (30).

Release the clutch. Remove the disc carrier and the set of discs (10). Remove the adjustment shims (8), the set of Belleville washers (9) and the ring (14). Remove the piston (13). Remove a screws (21) and take off the blade (18).

Take off the circlip (31) and remove the brake disc (20). Take off the brake disc. Extract the bearing (101) using an extractor. Take out the washer. Unscrew the nuts (210 and 211). Note the values of the nuts (210 and 211) if required. Remove the stops (116). Take out the control mechanism. Remove the pinions (118) and (118a).

Take out the shaft (35). If required, take off the external rings of the bearing. If necessary, remove the ram (217) and or (226). Take off the circlip (107), washer (108) and pinions. Remove the circlip (112). Release the pinion (118).

Massey Ferguson 7720, 7726 Power take-off clutch

1 - Shim, 2 - Taper roller bearings, 3 - Clutch cover, 4 - Cylindrical screw, 5 - Shim, 6 - Internal blade holder, 8 - Shim, 9 - Spring washer, 10 - Set of blades, 11 - Disc, 12 - Intermediate plate, 13 - Piston, 14 - Ring, 16 - Lip seal, 18 - Plate, 19 - Lip seal, 20 - Brake disc, 21 - Allen screw, 22 - Grower washer, 23 - Bush, 25 - Pinion, 28 - Taper roller bearing, 29 - Nozzle, 30 - Locking half-rings, 31 - Circlip, 32 - O’ring, 35 - Shaft, 36 - Taper roller bearing, 37 - Ring with rectangular section, 38 - Grub screw, 39 - Nozzle, 40 - Sensor, 42 - Shaft

MF 7720, 7726, 7480, 7495 Rear PTO drive

101 - Taper roller bearing, 102 - Shim, 104 - Clutch body, 105 - Roller, 107 - Circlip, 108 - Washer, 109 - Needle bearing cage, 110 - Spacer, 112 - Circlip, 113 - Taper roller bearing, 114 - Circlip, 115 - Allen screw, 116 - Stop, 118 - Pinion (1000 rpm), 118A - Pinion (540 or 750 rpm), 120 - Shaft, 121 - Circlip, 122 - Washer, 123 - Taper roller bearing, 124 - Shim, 125 - Grub screw, 126 - Spi seal, 127 - O’ring, 128 - Bearing cover, 129 - Cylindrical screw, 132 - Spacer, 133 - Threaded stud M10 x 50 - 10.9, 134 - Nut M10-10, 135 - PTO guard, 137 - End-fitting, 139 - Sensor, 140 - Allen screw

MF 7720, 7726 Rear PTO control

201 - Stirrup, 202 - Hexagonal nut, 203 - Stud, 205 - Allen screw, 206 - Hexagonal nut, 207 - Spacer pipe, 210 - Hexagonal nut, 211 - Hexagonal nut, 212 - Washer, 213 - Hexagonal nut, 214 - Roller, 216 - Allen screw, 217 - Rams, 218 - O’ring, 219 - Compact seal, 220 - Compact seal, 221 - Spring, 222 - Piston, 224 - Piston, 225 - Allen screw, 226 - Rams

Rear Power take-off cover

301 - Rear axle housing, 303 - Seal, 304 - Cover, 305 - Allen screw, 307 - Closing plug, 308 - Sealing ring, 309 - Closing plug, 310 - Sealing ring, 311 - Closing plug, 315 - Dowel pin, 316 - Housing cover, 317 - Screw M18 x 90 - 10.9, 318 - Screw M18 x 110 -10.9, 319 - Threaded stud M18 x 130 - 10.9, 322 - Sealing ring, 325 - Cylindrical screw

Disassembling Massey Ferguson 7720, 7726 Dyna VT transmission power take-off

Fit home the bearing (113) in the pinion (118a) and lock with the circlip (114), then fit the pinion (118) to its stop. Fit the circlip (112) on the opposite side.

Fit home the internal ring of the bearing (123) on the shaft (120). Position the washer (122). Fit the circlip (121). Smear the 2 grub screws (25) with plastic binder and tighten them until the internal ring of the bearing (123) reaches its stop.

The washer (122) must be fitted home. Fit the 1st needle bearing cage (109), the spacer (110) and the 2nd needle bearing cage (109) on the shaft (120). Fit the shaft (120). Position the washer (108). Fit the circlip (107). Fit new seals (219) in the ram (217).

Fit a new O’ring (218) in the groove of the ram (217). Smear the oil tight seals with miscible grease. Insert the piston (222) and spring (221) as indicated in the ram (217).

The oil tight seal (219) is comprised of 2 parts: an O’ring on the outside and a piston strip guide on the inside. Fit new seals (220) in the ram (226). Fit a new O’ring (218) in the groove of the ram (226). Smear the oil tight seals with miscible grease.

Insert the piston (224) and spring (221) as indicated in the ram (226). The oil tight seal (219) is comprised of 2 parts: an O’ring on the outside and a piston strip guide on the inside. Fit the rams (217 and 226). Smear the thread of the screws (216 and 225) with plastic binder and tighten the screws to the following torque: 49 Nm

Refit the hydraulic pipes which have been removed in the housing cover (316). If the housing is fitted with a new cover (316), screw the nozzle (29) to its stop in the threaded bore. Fit home the external ring of the bearing (36).

Smear 2 new rings (37) with miscible grease and install and lock them in the grooves of the shaft (35). Fit home the internal ring of the bearing (36).

When assembling a new shaft (35), smear the thread of the threaded stud (38) with plastic binder, and screw to its stop. Tighten the nozzle (29) to its stop. Fit the pre-assembled shaft (35) in the housing cover (316).

If required, fit compensating shims (124) and fit home the external ring of the bearing (123). Fit the pair of ring gears and the pinion (25).

Pre-assembling the stirrup

Smear the thread of the screws (205) with plastic binder. Fit spacers (207) and rollers (214). Tighten nuts (206). Insert the rollers (105) into the clutch body (104). Smear the thread of the screws (203) with plastic binder. Fit the stirrup tight to an identical distance, then loosen each screw (203) by 1/6 of a turn and lock them in this position.

Screw the nuts (ref. 210, 211 and 213) onto the rods of the pistons (222, 224). Fit the washers (212) with their chamfer turned upwards. Fit the pre-assembled stirrup (201). Fit the washers (212) with their chamfer turned downwards. Unscrew the nuts (210 and 211). Smear the thread of the screws (115) with plastic binder.

Fit the stops (116) and lock the screws (115). The following must be carried out before setting stirrup travel:
The oblong hole in the stirrup (201) must be turned towards the ram (226). Screw and lock the nuts (211, 210) to their stop. Screw a locally made eye nut M12 onto the piston rod of the ram (217).

Using a lifting tool, pull hard on the piston rod. (Coupling at 750 or 540 rpm). Check the clearance of the clutch body (104). Specified value: 0.1 to 0.2 mm clearance. If outside the specified clearance: Adjust with nuts M12 (top and bottom) until clearance of 0.1 to 0.2 mm is obtained.

Take off the lifting tool and unscrew the eye nut M12. Push the piston rod of the ram (226) fully in using a clamp, until the nuts (213) and at their stop. (Lifting limit, 1000 rpm position).

Check the clearance of the clutch body (104). Specified value: 0.1 to 0.2 mm clearance. If outside the specified clearance: Adjust the nuts (213) until clearance of 0.1 to 0.2 mm is obtained.

Take off the clamp. The coupling shifts to "Neutral" position. The 750 or 540 and 1000 rpm ring gears should be able to turn freely. The upward and downward free travel of the coupling should be identical. If not, readjust the coupling. Fit the shim (102). Fit the internal ring of the bearing (101) up against the shaft (120).

Fit the pinion (25). Smear a new O’ring with miscible grease and fit it in the groove of the shaft (35). Check the brake disc (20) for wear. If necessary, fit a new brake disc (20). Fit the circlip (31). Smear a new lip seal (19) with miscible grease and fit it in the brake disc groove, with the seal lips turned towards the oil chamber.

Fit the blade (18). Smear the thread of the screw (21) with Loctite, and fit the Grower washer (22) and socket (23). Tighten the screw. Smear a new lip seal (16) with miscible grease and fit it in the inner groove of the piston, with the seal lips turned towards the oil chamber. Fit the pre-assembled piston (13). Fit the ring (14).

Fit 5 Belleville washers (9) with the large external diameters facing each other, and the compensating shims (8). The external diameter of the first Belleville washer (9) should be turned towards the ring (14) of the piston (13). If required, for example if compensating shims (8) are lost, set the preload of the Belleville washer set (9).

Setting the preload of Belleville washer set

Remove the shim (5) from the internal disc carrier (6). Smear the thread of the screw (4) with plastic binder and tighten. Fit home the pre-assembled ring carrier (6).

Measure and note the distance between the disc carrier (6) and the end of the shaft (35). Example: 23.2 mm. Fit the compression tool and compress the set of Belleville washers (9). Fit the locking half-rings (30).

If the locking half-rings (30) are chamfered on just one side, the chamfered side must face the disc carrier (6). Remove the compression tool.

Measure and note the distance between the disc carrier (6) and the end of the shaft (35). Example: 25.8 mm. If the washer set gives compensating clearance of approximately 2.5 mm when completely compressed, the preload is correct. If not, correct it with compensating shims.