Specifications, Service and Repair of Farm and Lawn Tractors


Massey Ferguson 7622, 7624 Dyna 6 Transmission - Powershift module

Massey Ferguson 7622, 7624 Dyna 6 transmission (GBA15 gearbox) Powershift module is housed inside a housing located between the engine and the gearbox. It provides six ratios at the gearbox input for shifting under load.

Operating principle of the Powershift module and its control

MF 7622, 7624 Powershift module comprises:

- the multiplier module
- the Dynashift module.

The multiplier module

The multiplier module is controlled by proportional solenoids valves N and P.

It comprises:

- a standard epicyclic gear train;
- a clutch;
- a brake.

Direct drive (ratio 1/1)

The sun gear is attached to the planet carrier via the clutch. Drive enters via the planet carrier and exits via the ring gear.

Overdrive MF 7624, 7626 transmission (ratio 1.423/1)

The sun gear is immobilised on the gearbox housing by the brake. It allows the engine speed to go into overdrive when ratios E and F are engaged.

The Dynashift module

The Dynashift module provides four ratios for shifting under load - A, B, C and D - controlled by proportional solenoid valves L and N.

It comprises:

- two standard epicyclic gear trains (primary and secondary);
- two brakes;
- two clutches.

Drive enters and exits via the primary epicyclic gear train. The clutches/brakes operate on the secondary epicyclic gear train ring gear and sun gear at an opportune moment in order to modify the rotational speed of the primary sun gear, thus creating ratios A, B, C and D of the Dynashift module.

The clutches/brakes that select the multiplier module ratios and the Dynashift module ratios are each controlled by a piston P. When a brake is engaged, the related clutch is disengaged, and vice versa.

Control pistons P operate act both on brake discs F and on junction plate I. When piston P is under pressure, plate I pushes back Belleville washers B of clutch E.

When the pressure is released, Belleville washers B push piston P back via junction plate I and tightens clutch discs E.

Multiplier module

(1) Cover plate, (2) Screw, (3) Screw, (4) Screw, (5) Planet carrier, (6) Ring gear carrier, (7) Ring gear, (8) Planet gear, (9) Planet gear pin, (10) Input shaft, (11) Ball bearing, (12) Clutch Q bell housing, (13) Belleville washers, (14) Clutch Q/brake P junction plate, (15) Clutch Q discs, (16) Clutch Q intermediate plates, (17) Brake P discs, (18) Brake P intermediate plates, (19) Screw, (20) Clutch Q cover plate, (21) Snap ring, (22) Sun gear, (23) Dynashift module input shaft, (24) Ball bearing, (25) Planet gear needle rollers, (26) "O" ring, (27) Brake P piston, (28)Washer, (29) Lip seal, (30) "O" ring, (31) Spring, (32) Multiplier module housing, (33) "O" ring (34) "O" ring, (35) Ball bearing, (36) Splined washer (bronze), (37) Waved washer (spring), (38) Wear plate, (39) Wear plate, (40) Friction washer

Massey Ferguson 7624, 7622 Powershift module control

The Powershift module ratio can be changed via:

- the multifunctional Power Control lever located on the left underneath the steering wheel;
- the other lever fitted to the right-hand armrest.

In basic operating mode, ratios are shifted in Speedmatching mode. The most suitable ratio under load is then selected automatically when shifting range. Depending on the option, ratio shifting can be completely automatic.

Dynashift module

(40) Friction washer, (41) Thrust washer, (42) Screw, (43) Location of springs, (44) "O" ring, (45) Brake L piston, (46) "O" ring, (47) "O" ring, (48) "O" ring, (49) Brake N piston, (50) Screw, (51) Spring, (52) Rear cover plate of Dynashift, (53) Dowel, (54) Waved washer (spring), (55) Ball bearing, (56) Clutch M hub, (57) Circlip, (58) Snap ring, (59) Clutch M bell housing, (60) Belleville washers, (61) Clutch M/brake L junction plate, (62) Snap ring, (63) Primary planet carrier, (64) Planet gear pin, (65) Wear plates, (66) Primary ring gear, (67) Primary planet gear needle rollers, (68) Primary planet gear, (69) Wear plates, (70) Primary sun gear, (71) Screw, (72) Clutch O cover plate, (73) Clutch O bell housing, (74) Clutch O/brake N junction plate, (75) Belleville washers, (76) Clutch O discs, (77) Clutch O, intermediate plates, (78) Snap ring, (79) Clutch O hub, (80) Shaft/bell housings, (81) Spacer, (82) Ball bearing, (83) Ball bearing, (84) Screw, (85) Secondary sun gear, (86) Secondary planet carrier, (87) Brake N discs, (88) Brake N intermediate plates, (89) Secondary planet gear needle rollers, (90) Secondary planet gear,
(91) Planet gear pin, (92) Secondary ring gear, (93) Secondary ring gear carrier, (94) Screw, (95) Screw, (96) Secondary ring gear/bell housing, (97) Screw, (98) Brake L disc, (99) Brake L intermediate plates, (100) Waved washer (spring), (101) Screw, (102) Thrust plate, (103) Screw, (104) Snap ring, (105) Primary bell housing, (106) Bearing with sealed face, (107) Friction washer, (108) Bush, (109) Clutch M discs, (110) Clutch M intermediate plates, (111) Dynashift module housing, (112) "O" ring

Removing and refitting the Powershift module

Disconnect the MF 7622, 7624 tractor between housing (C) of the robotic gearbox and housing of the Powershift module (C1). Separate housing C1 from the engine.

Remove the hydraulic control unit located to the right of housing C1 together with its connecting pipes.

From housing C1 remove: the PTO shaft; the reverse layshaft; the reverse driven gear. Stabilise housing C1 of the Powershift module in a vertical position on wooden blocks.


Unscrew three screws (2) from the multiplier cover plate. In their place, fit locally obtained flanges B using screws V with the correct thread length.

Unscrew the eight M10 screws V2 without working on the M8 screws V1.

Unscrewing the M8 screws would cause the Powershift module to separate, which is not desired.Sling the Powershift module.

To remove the Powershift module from housing C1, proceed as follows:

- Using a suitable sling and hoist, lift the Powershift module slightly out of housing C1.

- Turn the Powershift module so that lug O of the reverse layshaft gear is positioned between the two bosses B.

- Tilt the Powershift module steeply towards lug O and continue to lift it so that it enters groove A (approx. D 310 mm) of housing C1.

- Definitively remove the Powershift module from housing C1.

Remove and discard seal J. Place the Powershift module in a vertical position on a suitable support S.


Lightly smear "O" ring J with miscible grease. Fit it into the groove of the Powershift module housing (111). Check that dowel P is present on housing C1. Clean mating face F of the Powershift module and that of housing C1.

If mating face F of housing C1 was chipped or deformed during the removal of the Powershift module, smooth it off with fine sandpaper.

To refit the Powershift module in housing C1, proceed as follows:

- Use flanges B and the sling used during removal.

- Mark the location of dowel P with a line of paint on housing C1 and on the Powershift module.

- Position the Massey Ferguson 7622, 7624 Powershift module at the opening of groove A of housing C1, positioning lug O of the reverse layshaft gear between the two bosses B.

- Tilt the Powershift module steeply towards lug O and continue to lower it so that it enters groove A of housing C1.

- When it has entered the groove of housing C1, continue to lower the Powershift module slowly, turning it gently to bring it into position with the paint lines made previously. Definitively refit the Powershift module in housing C1.

Screw the eight M10 screws V2. Tighten to 57-77 Nm. On the multiplier cover plate: Unscrew screws V. Remove the locally obtained flanges B. Screw in the original screws (2). Tighten to a torque of 37 Nm.

Stabilise front housing C1 of the Powershift module in a horizontal position. Refit: the reverse driven gear; the reverse layshaft; the PTO shaft.

Clean the mating faces: of the hydraulic cover plate; of the hydraulic control cover plate on housing C1. Check that transfer pipes T are present.

Lightly smear the mating face of the hydraulic cover plate on housing C1 with Loctite 510 or equivalent. Do not block low-pressure hydraulic port O (approx. 21 bar) supplying ranges 1 to 4 of the robotic gearbox.

Refit the hydraulic control unit. Screw in the screw. Tighten to 57-77 Nm. Fit housing C1 to the engine. Reconnect the tractor between housing C of the robotic gearbox and housing C1 of the Powershift module.