Specifications, Service and Repair of Farm and Lawn Tractors


Massey Ferguson 7616, 7618 Dyna 6 Transmission - GBA15 gearbox

Massey Ferguson 7618, 7616 gearbox (GBA-15) provides four basic synchronised ratios and six ratios for shifting under load.

The 24 ratios can be engaged manually or automatically inforward and reverse position, without using the clutch pedal. The gearbox is divided into two sections: front housing and rear housing.

View of the gearbox assembly

A - Dynashift module with multiplier module A1, Ar - Reverse multidisc clutch, Av - Forward multidisc clutch, B - Power Shuttle, C - Reverse driving gear, D - Main gearbox with four robotic ranges, E - Double cone synchroniser for 3rd/4th, F - Double cone synchroniser for 1st/2nd, G - Power take-off shaft, H - Main gearbox output shaft, I - Creeper gearbox (if fitted), L - Brake, M - Multidisc clutch, N - Brake, O - Multidisc clutch, P - Brake, Q - Multidisc clutch

Fitted behind the engine, the front housing supports:

- the multiplier module to obtain two ratios for shifting under load;
- the Dynashift module with four ratios for shifting under load;
- the PowerShuttle.

The multiplier module and the Dynashift module make up the Powershift module.

Fitted behind the front housing, the rear housing supports:

- the main gearbox with its four robotically-controlled mechanical ratios;
- the creeper gearbox.

MF 7616, 7618 Multiplier module

The multiplier module is fitted at the GBA15 gearbox input. It allows multiplier module ratios to be obtained by overincreasing respectively two ratios of the Dynashift module.

Multiplier module

(1) Clutch Q disc/intermediate plate assembly, (2) Brake P disc/intermediate plate assembly, (3) Spring, (4) Multiplier module housing, (5) Ring gear, (6) Planetary gear, (7) Needle bearing, (8) Pin, (9) Sun gear, (10) Ball bearing, (11) Ball bearing, (12) Ring-gear carrier, (13) Planet carrier, (14) Brake piston, (15) Clutch cover, (16) Friction washers, (17) Cover, (18) Input shaft, (19) Lip seal, (20) Ball bearing, (21) Clutch bell housing, (22) Belleville washers

The multiplier module includes:

- an epicyclic gear train;
- a brake;
- a multidisc clutch.

The brake piston, supplied by a proportional solenoid valve (with ON/OFF control), locks the brake discs.

The thrust plate moves forwards at the same time, compressing the two Belleville washers to release the multidisc clutch. The two multiplier module ratios are 1/1 and 1.423/1.

MF 7618, 7616 Dynashift module

This Dynashift-module provides four ratios for shifting under load plus ratios in combination with the multiplier module.

The Dynashift module includes two epicyclic gear trains:

- the primary epicyclic gear train, the main module component;

- the secondary epicyclic gear train, used to control the speed of the primary sun gear. This gear train is controlled hydraulically by the brakes via two proportional solenoid valves (with ON/OFF control) and two multidisc clutches under pressure from the Belleville washers.

Massey Ferguson 7616, 7618 gearbox PowerShuttle

The PowerShuttle is located in the centre of the gearbox. It connects the Dynashift module to the main gearbox.

The Power Shuttle includes:

- two multidisc clutches (front and rear) located back to back and controlled by two proportional solenoid valves with PWM control;

- a mainshaft providing the reversing function.

Main gearbox

The main gearbox has four ranges selected by two robotically-controlled double cone synchronisers (electrohydraulic). The main gearbox input drive is supplied by the multiplier.

Main gearbox

(89) Gearbox housing, (90) Shim(s), (91) Compartment, (92) Bearing cup, (93) Bearing cone, (94) Primary shaft, (95) Circlip, (96) Thrust washer, (97) Shim(s), (98) 1st/3rd double pinion, (99) Bearing cup, (100) Bearing cone, (101) Bearing cone, (102) Bearing cup, (103) Spacer, (104) Circlip, (105) Circlip, (106) Thrust washer, (107) Needle bearing, (108) Thrust washer, (109) Circlip, (110) Special circlip, (111) 3rd/4th double cone synchroniser, (112) 4th driving gear, (113) Ring, (114) Bearing cup, (115) Bearing cone, (116) Power take-off shaft, (117) Bearing cone, (118) Bearing cup, (119) Output shaft, (120) Needle bearing, (121) 4th driven pinion, (122) Spacer, (123) 3rd driven pinion, (124) 1st/2nd double cone synchroniser, (125) 1st driving gear, (126) Bearing cone, (127) Bearing cup, (128) 2nd gear pinion, (129) Bearing cup, (130) Bearing cone, (131) Circlip, (132) Thrust washer, (133) Shim(s), (134) Special spacer, (135) Bearing cup, (136) Bearing cone, (137) Shim(s), (138) Spring, (139) "O" ring, (140) Lubrication pipe

Dynashift and PowerShuttle modules

The four main gearbox ranges are automated. All ratios may be engaged or disengaged automatically by the tractor electronic control without intervention by the driver.

MF 7616, 7618 Dynashift module

(23) Thrust plate, (24) Friction washer, (25) Clutch bell housing, (26) Brake piston, (27) Ball bearing, (28) Needle bearing, (29) Secondary planet carrier, (30) Brake piston, (31) Pin, (32) Spring, (33) Needle bearing, (34) Brake N disc/intermediate plate assembly, (35) Clutch bell housing, (37) Friction washer, (38) Belleville washers, (39) Clutch O disc/intermediate plate assembly, (40) Rear cover, (41) Ball bearing, (42) Secondary sun gear, (43) Pin, (44) Planetary gear, (45) Secondary ring gear, (46) Secondary ring-gear carrier, (47) Ball bearing, (48) Primary sun gear, (49) Planetary gear, (50) Primary ring gear, (51) Primary ring-gear carrier, (52) Primary planet carrier, (53) Dynashift module housing, (54) Spring emplacement, (55) Brake L disc/intermediate plate assembly, (56) Clutch M
disc/intermediate plate assembly, (57) Belleville washers, (58) Primary shaft

Creeper gearbox

A unit mounted on the main gearbox output shaft is used to obtain slow forward speeds.

This mechanically-controlled unit encloses a traditional final drive giving a reduction of 4/1.


The lubricating oil is directed by the tractor hydraulic circuit.

It penetrates the two ports located to the left of the main gearbox and PowerShuttle housings respectively.

It lubricates the bearings, pinions and synchroniser hubs via axial channels and ports.