Does thicker PS fluid increase pressure?

[NICAT]

Hi.
I searched forum for finding information about how oil viscosity affect Power Steering performance. But unfortunately couldnt find detailed information.
So does using higher viscosity power steering fluid make steering wheel lighter ?
Regards.

 

[mk378]

No it would not. Thicker fluid does not flow as readily and is likely to reduce the system performance, unless the pump is worn and unable to generate pressure with a thin fluid.

The degree of power assist is set up by a spring in the control valve. The driver has to put some force on the wheel before the valve allows fluid pressure to work on the piston in the rack. It is designed not to be zero effort because that would have no "road feel" and make the car difficult to control.

 

[NICAT]

Originally Posted by mk378
No it would not. Thicker fluid does not flow as readily and is likely to reduce the system performance, unless the pump is worn and unable to generate pressure with a thin fluid.

The degree of power assist is set up by a spring in the control valve. The driver has to put some force on the wheel before the valve allows fluid pressure to work on the piston in the rack. It is designed not to be zero effort because that would have no "road feel" and make the car difficult to control.


Thanks for technically detailed answer.
So theoratically using softer spring may increase the performance ?
And how about using smaller pulley? (i do not feel any difference at higher RPMs. 600 vs 3000 rpm. . Should i ?)

 

[ABN_CBT_ENGR]

Originally Posted by NICAT


Thanks for technically detailed answer.
So theoratically using softer spring may increase the performance ?
And how about using smaller pulley? (i do not feel any difference at higher RPMs. 600 vs 3000 rpm. . Should i ?)


Yes, no, maybe, possibly but that depends on what or how you are defining performance.

The pump can only pump to the head allowed by the RPM

Pressure is determined by resistance to the flow ( cumulative back pressure)

The control valve has a minimum pressure

Once open its basic hydraulics- fluid moves piston and transmits both ways.

So what part of that are you wanting to alter?

 

[MolaKule]

Here are some files you can download to better understand hydraulic principles:

https://yuken-usa.com/pdf/special/Basic_Hydraulic_And_Components_(Pub._ES-100-2)_.pdf

https://www.hwhcorp.com/ml57000-012-ch1.pdf

https://abctlc.com/downloads/courses/HYDRAULICS.pdf

 

[NICAT]

Originally Posted by ABN_CBT_ENGR
Originally Posted by NICAT


Thanks for technically detailed answer.
So theoratically using softer spring may increase the performance ?
And how about using smaller pulley? (i do not feel any difference at higher RPMs. 600 vs 3000 rpm. . Should i ?)


Yes, no, maybe, possibly but that depends on what or how you are defining performance.

The pump can only pump to the head allowed by the RPM

Pressure is determined by resistance to the flow ( cumulative back pressure)

The control valve has a minimum pressure

Once open its basic hydraulics- fluid moves piston and transmits both ways.

So what part of that are you wanting to alter?


Thanks for answer.
What i meant by saying increasing performance was making steering wheel lighter to turn. Just thought that if some is good more is better

That is not criticallly important of course. Just wondered if there are any DIY method for this. Seemingly there is none

 

[NICAT]

Originally Posted by MolaKule
Here are some files you can download to better understand hydraulic principles:

https://yuken-usa.com/pdf/special/Basic_Hydraulic_And_Components_(Pub._ES-100-2)_.pdf

https://www.hwhcorp.com/ml57000-012-ch1.pdf

https://abctlc.com/downloads/courses/HYDRAULICS.pdf


Thanks sir