Load Sending hydraulic system (150 l/min) - Left-hand cover


The left-hand side cover, fitted on the intermediate housing, forms the support for the following components:
On its inside face 


- the booster pump (2) the capacity of which differs depending on the hydraulic characteristics as shown below.
- the suction manifold (4)

Load Sensing hydraulic circuit

Booster pump Variable                            Displacement pump
 60 cm3/rpm                                        0 à 45 cm3/rpm
80 cm3/rpm                                        0 à 60 cm3/rpm

On the outside face
- the 150 micron suction strainer (6) differs through the size of its filtering surface and depends on the capacity of the variable displacement pump (96 mm long with the 60 cm3 pump and 139 mm long with the 80 cm3 version).
- The figures given in this section are for the 60 cm3 pump and its surrounding elements. The construction of the 80 cm3 pump is identical in principle to the former.
- It should be noted however, that the internal pinions as well as the body of the pump have slightly different profiles.

Description

Pinion (1) taking its rotation from shaft (2), drives pinion (12) of the booster pump. The oil is sucked into the intermediate housing via the manifold (4). It is then directed towards the strainer (6) and the booster pump (2) through an internal channel in the cover. 


The oil is then discharged towards the variable displacement pump by the booster pipes (3) (54) held by compartment ‘C’ of the intermediate housing. The pipe (55) directs the oil coming from the 5 bar safety valve towards the suction manifold (4).

(25) O’ring (26) Mecanindus pin (54) Booster pipe
(55) Safety-valve pipe (depending on hydraulic characteristics)
A Suction
PCV To the variable displacement pump (depending on hydraulic characteristics)
VS 5 bar safety-valve
C Compartment of the intermediate housing


Parts list
(1) Nut (2) Booster pump (3) Booster pipe (4) Suction manifold (5) O’ring (6) Strainer (7) Studs (8) Plug (9) Seal (10) Bolt (11) Washer (12) Pinion (13) Key (14) Cover (15) Nut (16) Centring pins (17) O’ring (18) Gasket (19) Bolt (20) Bowl (21) O’ring (22) Bolt (23) O’ring (24) Locating pins

A : Suction from manifold (4)
B : Strainer (150 microns)
G : Booster supply to the variable displacement pump

Removing and refitting the cover

Removal
Take off the wheel on the side concerned. Position an axle stand.


Partially drain the intermediate housing. Unscrew the bowl (20). Remove the strainer (6). 


Take off nuts (1) and bolts (10) (19). Remove the cover (14) and then the suction manifold (4). If necessary, remove the studs (7).

Refitting
Clean the mating faces of the housing and the cover. Smear the mating face of the housing with Loctite 510 or its equivalent.
Replace the O’ring (17) and position the seal (5) on the suction manifold (4).
Refit manifold (4), the end fitted with seal (5) inserted into compartment ‘C’ of the intermediate housingLightly smear the face of the gasket (18) on the suction manifold (4) with Silicomet type silicone. Spool the gasket over the studs (7), the adhesive facing the cover. Screw two diametrically opposed guide studs G on to the intermediate housing.


Check for the presence of the two centring pins (16). Place a new O’ring (25) on the booster pipe (3). Insert the pipe, its end positioned in the Mecanindus pin (26). Spool the cover on to the guide studs G and studs (7). Using a bronze hammer, tap the cover to engage the pins (16) in the housing.
Take out the guide studs G. Fit and alternately and uniformly tighten the bolts (10) (19) to a torque of 90 - 120 Nm.
In case of any resistance felt while tightening, move the cover away from the housing and check the position of pipe (3) in the pump port. Also turn pinion (12). Fit nuts (1) smeared with Loctite 241 and tighten to a torque of 15 - 20 Nm. If necessary, replace O’ring (21) on bowl (20). Put the strainer (6) in place and tighten the bowl. Carry out operations in reverse order. Check the oil tightness of the mating face of the cover as well as that of the bowl.
Tightening torques:
- Nuts (1): 15 - 20 Nm (Loctite 241)
- Bolts (10) (19): 90 - 120 Nm
- Wheel nuts or studs
- Bowl (20): moderate tightening.

Removing and refitting the booster Pump

- The removal and refitting procedures are the same for a 60 cm3 or 80 cm3 pump. Take off the cover.

Removal
Remove bolts (22) and pump (2). If necessary, remove pinion (12) from the pump. Recover key (13).

Refitting
Clean the mating faces of the pump and cover.
Check for the presence of the locating pins (24).


Inside the cover, apply a bead ‘C’ of Loctite 574 or its equivalent around the bolt holes. The diameter of the bead should be small in section so as to not touch the groove of seal (23). Fit a new seal.
If disassembled, replace key (23) and refit pinion (12). Tighten nut (15) to the torque indicated below. Position the pump on the centring pins.
Fit bolts (22) smeared with Loctite 241 or its equivalent and tighten to a torque of 40 - 50 Nm. Manually check the rotation of the pump. Refit the cover. Tightening torques
- Nut (15): 50 - 60 Nm (Loctite 241)
- Bolt (22): 40 - 50 Nm (Loctite 241)

Replacing the booster pump seals 


- Whatever the hydraulic characteristics of the pump, the operational procedure for the replacement of the seals remains identical. Remove the left-hand side cover and the booster pump.

Disassembly


Tighten the pump in a vice fitted with plastic jaw protectors. Remove bolt (1) and cover (7).


Take off circlip (3), seal (4) and O’rings (5) (6).

Refitting
Lubricate seal (4) and insert it using an appropriate fixture. Place circlip (3).


Lightly smear the O’rings (5) (6) with miscible grease and position them on the cover (7).


Position the cover. Fit and tighten bolts (1) to a torque of 30 - 40 Nm.
Manually check for the free rotation of the pump. Refit the booster pump and the left-hand cover.