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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.
Lubrication
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.
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