Last update:

08/03/2005

  Power Steering

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Power Steering

New features and modifications over the Ford Granada

bulletNew steering gear for the new steering geometry.
bulletNew reservoir and lines.
bulletNew height and reach-adjustable steering column.
bulletNew steering column remote radio control stalk.
bulletSteering wheels as for MY '94, optionally with speed control buttons and/or in leather.
 

Steering Column

Location of the power steering
components according to engine
 
A Left-hand drive variant
B Right-hand drive variant

1 Power steering fluid reservoir
2 Power steering pump - DOHC engine
3 Steering gear
4 Cooling loop
5 Power steering pump - V6 24V engine
6 Power steering pump - Diesel engine

 
ZF Servotronic power steering (awaiting diagram)

The ZF Servotronic is a power steering system the power assistance of which is controlled electronically according to the vehicle speed.

It is available in conjunction with 24V engines.

Construction
The ZF Servotronic essentially consists of
 
bulletfluid reservoir (16),
bulletpump with control valve (14 in detail A)
bulletsteering gear with valve housing (19, 20)
bulletelectronic speedometer (1)
bulletspecial power steering module (2)
bulletelectro-hydraulic transducer (3)

The valve housing accommodates

bullettorsion bar (10)
bulletrotary slide valve (12)
bulletcontrol sleeve (13)
bulletreaction piston (8)

Operation without vehicle speed signal

The torsion bar (10) is connected at the top to the rotary slide valve (12) and at the bottom to the pinion (20) and the control sleeve (13).

When the steering wheel is turned, the rotary slide valve (12) rotates together with the pinion (20), control sleeve (13) and reaction piston (8) in the valve housing (23).

The torsion bar (10) is deformed elastically by the torque transmitted through the steering column. This produces a radial movement of the rotary slide valve (12) in relation to the

control sleeve (13). The hydraulic fluid coming from the pump is passed to the appropriate side of the working piston (24) in the steering gear.

The reaction piston (8) remains inoperative.

Operation with vehicle speed signal

The effect on the working piston (24) remains the same.

The steering module receives a vehicle speed signal from the electronic speedometer (1) and sends a flow signal corresponding to this speed to the electro-hydraulic transducer (3).

Depending on this flow signal, the valve in the electro-hydraulic transducer (3) is opened a greater or lesser amount and opens the hydraulic passages to the reaction piston (8).

On the inside the reaction piston (8) is connected to the rotary slide valve (12) by means of three axial ball guides. On the outside it is connected to the control sleeve (13) by means of a ball thread with four turns.

The axial movement of the reaction piston (8) caused by the action of the hydraulic fluid is converted by the ball thread into a radial movement which counteracts the radial movement of the rotary slide valve (12).

The valve housing (23) accommodates the reaction limiting valve (4) which has the task of limiting the pressure to the reaction piston (8) and allowing surplus fluid to pass to the return.

 

 

 

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