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Massey Ferguson 7624, 7626 hydraulic system – right-hand cover

MF 7400-7700 Series Tractors Repair Operations

Massey Ferguson 7624, 7626 tractors may be fitted with a 150 l/min flowrate Load Sensing circuit.

The right-hand side hydraulic cover of this circuit is fitted on the intermediate housing as is the 110 l/min flowrate Load Sensing circuit.

The cover serves as a support for numerous components and contains various channels for the booster, lubricating and low flowrate circuits.

On its internal face, the cover contains:

- an idler pinion (82) also known as the "relay" pinion.
- the safety valve (44) of the booster and lubricating circuit calibrated at 5 bar.
- the safety valve (45) of the low pressure circuit (17 bar).

On its external face, the cover is fitted with:

- the variable displacement pump (41) and its regulator (12)

- the main 15 micron filter (27)

- one or two priority block(s) (7) (depending on assembly) serving the various functions of the low and high flowrate circuits

- the high pressure relief-valve (2) calibrated at 230 bar

- the four solenoid valves (15) to (18) controlling the low pressure functions (depending on options) one of which (power take off clutch) is of the proportional type.

- the high and low pressure diagnostics connectors (11) (48), booster (lubrication) (29) and Load Sensing (9).

- the low pressure (14) and booster (42) switches as well as the clogging indicator (34) of the main filter (27).

MF 7624, 7626 Hydraulic routing

- The engine movement transmitted to pinion by shaft drives the variable displacement pump pinion via the "relay" pinion (82).

- The oil coming from the booster pump located on the left-hand cover flows into the priority block(s) (7) (depending on version) via the main filter (27) and the variable displacement pump (41).

- The tube (55) sends the oil coming from the 5 bar safety-valve into the suction manifold of the booster pump when no hydraulic slave device is used.

(1) Bolt (2) High pressure relief-valve (3) Orbitrol spool valve supply port (4) Bolt (5) Load Sensing control port from Orbitrol spool valve (6) Load Sensing control port to pump regulator (7) Priority block(s (8) Cover (9) Load Sensing diagnostics connector (10) Return pipe (11) High pressure diagnostic connector (12) Pump regulator (13) Load Sensing union (14) Low pressure (17 bar) switch (15) Solenoid valves: power take off, power take off to brake, differential lock front and rear if fitted and (18) 4WD (19) Hydraulic cover assembly (20) Park Lock union (21) Power take off clutch port (22) Mecanindus pin (23) Power take off brake (24) 2WD or 4WD differential lock port (25) O’ring (26) Port for 4WD union (27) 15 micron main filter (28) Low pressure port (29) Booster pressure and lubricating diagnostic connector (30) Supply port for lift control valve and auxiliary spool valves via the manifold (31) Load Sensing control port from auxiliary spool valves and lift control valve (32) Bolt

(33) Control port of trailer brake valve (34) Clogging indicator (35) O’ring (36) Centring pins (37) Nut (38) Washer (39) Pump pinion (40) Key (41) Variable displacement pump (42) Pressure switch (booster and lubrication) (43) Port to lubricating manifold located above centre housing (44) 5 bar safety valve (45) 22 bar safety valve (46) Plug (47) Bolt (48) Low pressure diagnostic connector (49) Rivets (50) Port to trailer braking quick disconnect coupling (51) Transfer pipe (56) Composite seal (O’ring and anti-extrusion bush) (57) Dust cover (58) Sleeve (59) O’ring and dust cover (60) O’ring and dust cover (61) Composite seal (O’ring and anti-extrusion bush) (62) Dust cover (63) Suction manifold and bolt (64) Discharge manifold and bolt (65) Lubricating port for relay pinion (66) Port to brake power assistance (67) Studs (68) Nuts (69) Plug (70) Closing plate and seal (71) Plug (72) Spacer (73) Bolt (74) Obturator and seal (75) Bolt (76) Washer (77) Bearing cone (78) Bearing cup (79) Shim(s) (80) Circlips (81) Spacer (82) Idler pinion (83) Pin (84) O’ring

(22) Mecanindus pin (52) O’ring (53) O’ring (54) Booster pipe (55) Safety valve (44) pipe, A - Suction, PCV - To variable displacement pump (41), VS - 5 bar safety valve (44), C - Intermediate housing compartment

Removing and refitting the cover

Immobilise the MF 7624, 7626 tractor. Chock the left rear wheel. Chock between the frame and the front axle. Partially drain the intermediate housing. Disassemble the right rear wheel. Position an axle stand.

Removing the priority block(s)

Proceed with the removal of the priority block(s) by removing bolts (4) after previously disconnecting hose pipes (3) (5) (6) (28) (30) (31) (50).

On Massey Ferguson 7624, 7626 tractors fitted with trailer braking, remove the priority block(s) (7) without disconnecting hose (33).

This precaution will avoid bleeding of the valve pilot circuit when refitting the cover.

Removing the cover

Disconnect pipes (10) (21) (23) (24) (26) (43), the solenoid valve harnesses (15) to (18) (depending on the version) and switches (14) (34) (42).

Take out bolts (32) and remove the main filter assembly (27). Remove bolts (1) and nuts (68). Check that there is no hydraulic or electrical link that remains connected between the cover and the intermediate housing. Release and remove the cover.

Certain nuts and bolts on the cover are difficult to access. Where necessary, use a locally manufactured wrench. After removing the cover, take out pipes (54) (55) (optional).

The 22 bar safety valve (45) comprises: circlip, stop, spring (3) and valve.

Refitting the cover

Check for the presence of rivets (49) at the end of the channels located on the external and internal faces of the cover. Clean the mating faces of the housing and the cover.

Check for the presence of the two centring pins.

If removed:

- place seal (53) on pipe (55). Position the end of the pipe in the Mecanindus pin (22) located on compartment "C" of the intermediate housing.

- place seal (52) on pipe (54). Position the machined slot of the flange in pin (1). Lightly smear the seal (4) with miscible grease and stick it to the flange.

Check the location of the pins (67) in the intermediate housing.
The pins are first lightly smeared with Loctite 241 before fixing them on the housing.
Smear the mating face of the housing with Loctite 510 or its equivalent.

With the assistance of another operator and the tool recommended in the preceding remark "Danger", refit the cover by aligning its holes with the studs on the housing.

Push the cover progressively while simultaneously checking between housing and cover mating faces that the 5 bar safety valve is correctly housed in pipe (55).

Tighten bolts (1) and nuts (68) to a torque of 120 - 160 Nm. If there is any resistance, stop tightening and open the gap between housing and cover to check on the correct alignment of pipe (55) and the 5 bar valve.

Refit the main filter assembly (27) and tighten bolts (32). Reconnect the harnesses to the solenoid valves and switches. Carry out operation in reverse order.

Refitting the priority block(s)

Refit the priority block(s) and check for the presence of seals. Tighten bolts previously smeared with Loctite 542 to a torque of 25 - 35 Nm. Reconnect the pipes or hoses. Carry out operation in reverse order.

Refit the rear wheel. Remove the axle stand. Tighten the wheel nuts or studs (depending on version). Top up the oil levels in the housings and check the transparent tube on the left-hand side of the centre housing. Remove the chocks.

Start the engine and check:

- the operation of the hydraulic and electrical components
- the oil tightness of the mating faces, pipes and hoses.
- If the variable displacement pump has been replaced, carry out hydraulic tests. Carry out a road test.