Specifications, Service and Repair of Farm and Lawn Tractors

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Massey Ferguson 6614, 6615 tractor electrohydraulic auxiliary spool valves

The Bosch/Rexroth SB23 LS spool valves controlling supply to the Massey Ferguson 6614, 6615 hydraulic couplers are comprised of: hydraulic and electrohydraulic part.

An electrohydraulic part comprising:

- an ON/OFF solenoid valve and a 3-way pressure relief valve located on the end plate of the spool valve block,
- a pilot valve fitted in the electrohydraulic unit.

This section shall concern the hydraulic part only. The Bosch/Rexroth SB23 LS electric hydraulic control spool valves are supplied by high flow rate, high pressure oil from the priority blocks.

When no functions are being activated, the entire flow rate is directed towards the spool valves. When certain functions are being supplied, the excess flow then remains available to the auxiliary spool valves.

The adjustment of the flow rate, expressed as a percentage, may be displayed on the onboard computer (Datatronic) by the operator.

The MF 6614, 6615 tractor electric hydraulic spool valves controlled by a Joystick are fitted with a floating Kick-out position (automatic return to neutral).

The main spool of the spool valve directs oil towards the outlet ports A or B. Each outlet port is linked to the LS pilot line of the variable displacement pump regulating valve via the priority block(s).

The spool valves consist of both electronic and hydraulic components, the latter containing spools and valves. Some elements cannot be repaired as spare parts.

Different types of spool valve block components

A spool valve block can consist of three, four or five of the following components. It can combine components of similar type of or different types.

Component a - Electrohydraulic component (Joystick)
Component b - Electrohydraulic component (Dual Control)
Component c - Mechanically controlled component.



(1) Auxiliary spool valves (6) End plate (14) Inlet block (17) Lift control spool valve (18) ON/OFF solenoid valve (19) Electronic units

Operation of the pressure relief valve and electrohydraulic unit

When the ON/OFF solenoid valve located on end plate is open, the flow from the pump is directed to the 3-way pressure relief valve.

The 3-way pressure relief valve supplies the pilot valve with a pressure of 21 - 24 bar via a pressure balancing valve.

The pilot valve receives a signal from the digital device and moves the main spool of the auxiliary electric hydraulic spool valve according to the information received from the Joystick.

The digital device is informed of the position of the main spool by a displacement sensor. The pilot valve and the digital device are housed in the unit fixed below the spool valve.

The pilot valve is protected from possible oil contamination by a set of FP filters (25 microns).

Electronic unit (2) channels P and R are connected to channels P1 and R1 of the MF 6614, 6615 auxiliary electrohydraulic spool valve.



(1) Main electric hydraulic valve spool (2) Electrohydraulic unit (3) Return spring (4) Piston (5) Pilot valve (6) Digital electronic system (7) Displacement sensor, FP - Set of filters (25 microns), P - Pressure, R - Return

Operation of the auxiliary electric hydraulic spool valve

When the spool is moved electric hydraulically upwards by the pilot valve, oil penetrates via channel P and travels to the flow regulation control spool restrictor and the grooves of the main spool.

The oil is then carried towards a main channel and lifts the ball of valve to enter a chamber. Displacement of the spool simultaneously opens the one-way valve.

The oil flows from the chamber towards port B and returns to the housing through port A via the hydraulic slave device. The operating principle is identical when the spool is electro hydraulically moved down by the pilot valve.

The oil then flows from the chamber towards port A and returns to the housing through port B via the hydraulic slave device. The electrohydraulic spool valves can be manually controlled using a lever screwed onto the reversing lever.

Layout of components and identification of ports



(1) Main spool (2) Valve (3) Non-return valve (4) Pressure balancing valve (5) Cover

Spool valve assembly

On Massey Ferguson 6615, 6614 tractors where one or more elements of the auxiliary spool valves are operated mechanically, take care to disconnect the link cable(s) without turning the main spool of the valve a half turn.

Place the lift arms in the low position.

Disconnect:

- on mechanically operated spool valves - control cable, taking the above reminder into consideration;

- on Joystick or lever operated (Dual Control) spool valves - solenoid valve, connector(s) linked to the spool valve electrohydraulic unit(s), marking their position(s).

Removing the spool valves

The spool valve block assembly must be removed complete before working on it. Any operations carried out on the spool valves require scrupulous cleanliness.

First correctly clean the spool valves (lift control and auxiliary) and the areas around them before removing them.

If necessary, remove all the spool valves one after the other and disconnect the hydraulic connections as they are removed.

Removing the lift control spool valve

Take off the supply and return pipes. Disconnect the connectors of the lifting and lowering solenoid valves.

The brown connector is connected to the right-hand solenoid valve used to lower the lift control.

Remove the spool valve assembly. Remove lift control spool valve.

Removing the inlet block

In order to fit the MF 6615, 6614 auxiliary spool valves in horizontal position, it is necessary to remove the spool valve block assembly.

Loosen the P – R and LS unions, disconnect the hydraulic union and electrical connectors, and remove the spool valve block. Remove the inlet block.

Install the spool valves

Wipe clean the mating faces of the inlet block, the lift control spool valve, the auxiliary spool valves and the end plate.

Check that each element is perfectly flat.

Check the tightness of the studs on the inlet block.

Position the new seals (2) (3) (4) and (5) on each element of the distribution block (1).



Assemble the distribution block on the workbench by superposing the elements and following the assembly procedure.

Reinstall fit the complete block on the Massey Ferguson 6614, 6615 tractor.

Reconnect the hydraulic pipes and electrical connectors.

Reconnect:

On mechanically operated spool valves

- the lifting and lowering solenoid valve connectors in accordance with marks made during removal,
- the control cable(s);

On Joystick or lever operated (Dual Control) spool valves

- the lifting and lowering solenoid valve connectors in accordance with marks made during removal,
- the connector(s) linked to the electrohydraulic unit(s), according to marks made during removal,
- the solenoid valve located on the end plate.

Start the engine, place the lift control arms in the low position.

At each position, check the operation of:

- the hydraulic system.
- electronic system.

Check the oil tightness of the spool valves and hydraulic unions.

Assembly procedure

To obtain the correct assembly of seals (2) to (5), the reassembly of each spool valve must be carried out vertically on the workbench.



In this order, stack the input unit, an auxiliary spool valve, a support block, the lift control valve, an additional support block, and the auxiliary spool valves.

Place a steel ruler R thrust against face F of the distribution block so as to align the fixing points equally and correctly.

Tighten the nuts to a torque of 30 - 33 Nm. After the assembly of the spool valves, carry out the reassembly operations.

 

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