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Massey Ferguson 7485, 7480 closed centre hydraulic system principle

MF 7400-7700 Series Tractors Repair Operations

The purpose of the Massey Ferguson 7480, 7485 closed centre hydraulic system (150 l/mis) to limit the power absorbed by the engine. If no hydraulic slave device is actuated, no flow is discharged by the variable displacement pump.

When a function is activated, the pump only supplies the output required for that function. If the housing is drained, or if the main filter is replaced or any servicing operation carried results in the air intake into the system, it is essential to prime the hydraulic circuit.

Disconnect the connector to the fuel injection pump. Activate the engine starter motor in consecutive bursts until the (red) booster pressure signal lamp on the dashboard goes out.

MF 7485, 7480 Centre housing lubricating circuit

A - Trumpet housing lubrication, B - Centre housing lubricating manifold, C - Pump bearing lubrication, D - General supply from booster circuit, E - PTO clutch lubrication, F - Handbrake mechanism lubrication and creeper unit (if fitted), G - Transfer pipe for trumpets with double drive unit

Layout of components in MF 7480, 7485 Powershift gearboxes

(1) Tank (2) Brake master cylinders (3) Servo brake (4) Proportional solenoid valves of gearbox(13) Main filter (14) Suction strainer (15) Pump (16) Variable displacement pump controller(17) Load Sensing diagnostic connector (18) Solenoid valves: PTO brake, differential lock to (front, rear) (21) and 4WD (22) Steering priority spool valve (23) 17 bar pressure spool valve(24) High pressure diagnostic connector (25) 5 bar safety valve (26) 22 bar safety valve (27) Priority block without trailer braking (28) Right-hand cover (29) Booster pump pressure diagnostic connector (30) Low pressure diagnostics connector (31) Discharge pressure limiter (32) Lift rams (33) Couplers (34) PTO brake (35) PTO clutch (36) Auxiliary spool valve (37) Suction strainer (150)(38) Booster pump (39) Centre housing lubricating manifold (40) 4WD clutch (41) Lift control valve(42) Rear differential lock (43) Left-hand.t cover (44) 3-way filter (45) Temperature probe (46) Gearbox pressure regulating valve (17 bar) (47) Hydrostatic steering spool valve (Orbitrol)(48) Variable displacement pump (49) Thermostatic valve (50) Front differential lock (51) Steering rams(52) Oil cooler (53) Pump drive pinion bearing

Version Massey Ferguson 7485, 7480 tractor without trailer braking

(54) Park Lock control (55) Park Lock solenoid valve (58) Braking assistance accumulator (62) Priority blocks with trailer braking (63) Trailer brake valve (64) Trailer brake coupler (65) High pressure spool valve (A) Port and suction pipe of the Gerotor pump (B) Return port (Orbitrol and braking assistance) (C) Intermediate housing (D) Gearbox (E) Engine speed sensor (F) Tank and brake master cylinders

Diagram of Full Powershift gearbox

- 150 l/min Load Sensing optional
- A: Dana front axle version
- B: ZF front axle version

(1) Tank (2) Brake master cylinders (3) Servo brake (4) to Gearbox proportional solenoid valves (13) Main filter (15) (14) Suction strainer (250) (15) Pump (16) Variable displacement pump controller (17) Load Sensing diagnostic connector (18) Solenoid valves: PTO, PTO brake, differential lock to (front, rear) (21) and 4WD (22) Steering priority spool valve (23) 17 bar pressure spool valve (24) High pressure diagnostic connector (25) 5 bar safety valve (26) 22 bar safety valve (27) Priority block without trailer braking (28) Right-hand cover (29) Booster pump pressure diagnostic connector (30) Low pressure diagnostics connector (31) Discharge pressure limiter (32) Lift rams (36) Auxiliary spool valve (37) Suction strainer (150 ?) (38) Booster pump (39) Centre housing lubricating manifold (41) Lift control valve (43) Left cover (44) 3-way filter (15 ?) (46) Gearbox pressure regulating valve (17 bar) (47)
Hydrostatic steering spool valve (Orbitrol) (48) Variable displacement pump (49) Thermostatic valve (51) Steering ram(s) (52) Oil cooler (54) Park Lock control (55) Park Lock solenoid valve (56) Dual Control or front PTO (if fitted)17 bar hydraulic Line (57) Braking assistance non-return valve (58) Braking assistance accumulator (59) Load Sensing connector (provision for) (60) Return connector (provision for) (61) High pressure connector (provision for) (62) Priority blocks with trailer braking (63) Trailer brake valve (64) Trailer brake coupler (65) High pressure spool valve (66) Intermediate pinion lubrication