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Massey Ferguson 6485, 6490 Dyna 6 Transmission construction

MF 6400-6600 Series Tractors Repair Operations

Powershift module and Power-Shuttle

Massey Ferguson 6490, 6485 Dyna 6 transmission Powershift module is fitted behind the engine flywheel.

The Powershift module comprises:

- the multiplier module;
- the Dynashift module.

Each module is fitted in a cast-iron housing screwed into the front gearbox housing.

Multiplier module

MF 6485, 6490 Dyna 6 Transmission 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 comprises an epicyclic gear train, a clutch and a brake. The input shaft (18) is linked to the planet carrier (13). It drives the power take-off shaft via the vibration damper located in the engine flywheel.

The clutch discs (1) are splined to the input shaft (18). The intermediate plates of the clutch (1) are integral with the clutch bell housing (21) and sun gear (9).

The brake discs (2) are connected to the clutch bell housing (21) and sun gear (9). The ring gear (5) and ring gear carrier (12) of the epicyclic gear train drive the primary shaft of the Dynashift module.

Dynashift module

The Dynashift module comprises two epicyclic gear trains (primary and secondary), two brakes and two clutches.

MF 6490, 6485 Dyna 6 Transmission 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

Primary epicyclic gear train

The ring gear (50) of the primary gear train is splined to the primary shaft (58). It rotates at the multiplier secondary speed.

The planet-carrier (52), linked to the shaft/Power-Shuttle bell housings, supplies output rotational speed to the Dynashift module.

The sun gear (48) on the primary epicyclic gear train is connected to the planet-carrier (29) on the secondary epicyclic gear train.

Secondary epicyclic gear train

The secondary gear train (45) ring gear can be locked in rotation by the brake (55) or fixed to the primary shaft (58) by the multidisc clutch (56).

The secondary sun gear (42) can be locked in rotation by the brake (34) or fixed to the shaft/PowerShuttle bell housings by the multidisc clutch (39).

The secondary planet-carrier (29) is fixed to the sun gear (48) on the primary epicyclic gear train.

Clutch/brake operation

The clutches/brakes that select the Massey Ferguson 6485, 6490 Dyna 6 Dynashift module ratios are each controlled by a piston.

When a brake is engaged, the related clutch is disengaged, and vice versa. The control pistons act both on the brake discs and on an intermediate plate.

When the piston is pressurised, the plate pushes back the Belleville washers of the clutch. When the pressure is released, the Belleville washers push the piston back via the intermediate plate and tighten the clutch discs.

PowerShuttle: reverse

Reverse is provided by a mainshaft comprising a shaft and two pinions.
It transmits drive from the PowerShuttle to the 2nd gear pinion on the main unit output shaft.
The pinions are splined to the shaft.
The pinion is mounted on different size taper roller bearings, shimmed with preload under the bearing cup.

Main gearbox construction

The main gearbox is crossed entirely by the power take-off shaft (116) which links the engine flywheel to the power take-off clutch at the front of the rear axle. This shaft turns at the centre of a series of shafts forming the upper shaftline.

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

A vertical compartment (91) in front of the main gearbox housing (89) supports the front bearings (92)(93) and (135)(136) on the primary (94) and output (119) shafts. It is also fitted with the lubricating channels.

The main gearbox front and rear housings are bolted together and act as an oil tank for the MF 6485, 6490 tractor hydraulic circuit.

The main gearbox has four synchronised ratios with two double cone synchronisers. Four gear trains are divided between two shafts (94) (119). Each range is engaged via a synchroniser.

A safety finger on the selection mechanism prevents two ranges being engaged simultaneously. The first ratio uses three gear trains. The last three ratios each use one gear train (see kinematics).

Primary shaft

The primary shaft (94) is supported by two taper roller bearings (92)(93) and (114)(115). It is preloaded under the bearing cup (92) using the shims (90).

On the primary shaft (94), the double 1st/3rd gear pinion (98) forms a single unit supported by:

- two taper roller bearings (99)(100) and (101)(102) fitted in an X shape;
- a needle bearing (107).

The position of the double pinion should be checked (98) in relation to the special circlip (110), so that the 3rd/4th gear double cone synchroniser (111) synchronises range 3 correctly.

The taper roller bearings (99)(100) and (101)(102) are shimmed with a slight clearance or a slight preload using the shims (97).

The machined teeth on the primary shaft (94) mesh constantly with the 2nd driven pinion (128) on the output shaft (119). The 4th gear pinion (112) turns freely on a ring (113) fitted with a lubricating port.

Output shaft

The primary shaft (119) is supported by two taper roller bearings (117)(118) and (135)(136). It is preloaded under the bearing cup (135) using the shims (137).

The 2nd gear driven pinion (128) turns freely on the output shaft (119). It is supported by:

- two taper roller bearings (126)(127) and (129)(130) fitted in an X shape;
- a needle bearing (120).

The taper roller bearings (126)(127) and (129)(130) are shimmed with a slight clearance or a slight preload using the shims (133).

The 2nd gear driven pinion (128) acts as a rotating axis for the 1st driving gear (125), which turns without a bearing thanks to a consequential, specific heat treatment.

The friction surface is lubricated through radial ports. The 1st/2nd gear double cone synchroniser (124) is splined to the 2nd gear driven pinion (128).

It attaches this to the pinions (125) or (123) according to the range engaged. The 3rd (123) and 4th (121) gear driven pinions are splined to the output shaft (119).