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Old 7th December 2008, 14:39   #1
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Default Power Steering masking Suspension Problems ?

Bhpians,
Recently I drove a friendís car (no power steering) which had a tyre problem. This was causing the steering to vibrate violently at a slow speed.
This set me to think: what if my car (which has a hydraulic power steering) had the same tyre problem, or for that matter any suspension / tyre problem which causes the steering to drift to one side or vibrate or any other symptom.

Would I be able to feel these symptoms or would the power steering damp or mask these problems and make it seem like there is no problem at all?
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Old 7th December 2008, 16:01   #2
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yes you will be able to feel the vibrations!
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Old 7th December 2008, 18:10   #3
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There is no connection between the two. Power assistance is only for turning. You will get the same vibration feedback on your steering wheel.

A routine service of your tyres should anyways keep you away from this fear.
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Old 8th December 2008, 12:29   #4
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But in case of EPS - how can you possibly get vibrations?

EPS is just like toy steering system. There is absolutely no linkage between the wheels/suspensions and the steering wheels.

Ofcourse, if EPS simulates the feedback received from the rack, then you would get the feedback on the steering wheel.
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Old 8th December 2008, 12:50   #5
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Quote:
Originally Posted by alpha1 View Post
But in case of EPS - how can you possibly get vibrations?

EPS is just like toy steering system. There is absolutely no linkage between the wheels/suspensions and the steering wheels.

Ofcourse, if EPS simulates the feedback received from the rack, then you would get the feedback on the steering wheel.
there is a study paper on EPS titled "An EPS Control Strategy to Reduce Steering Vibration Associated with Disturbance from Road Wheels"

Abstract below:

This paper presents a new control strategy for Electric Power Steering (EPS) to reduce steering vibration associated with disturbance from road wheels. Disturbance from road wheels may cause undesirable steering vibration if drivers run on an unpaved road or road wheels are not well balanced. For drivers, road information generated by alignment torque is essential to steer a vehicle easily. However drivers are unpleasant for steering vibration associated with disturbance from road wheels. InŅthe steering system, both of them are transmitted to the driver through steering mechanism. We have developed a new EPS control strategy that reduces steering vibration associated with disturbance from road wheels without influencing road information generated by alignment torque considering the difference in frequency. The new EPS controller is constructed based on damping for specified frequency using the motor angular- velocity. We experimented with this proposed control algorithm using a test vehicle and confirmed that it enables reduced steering vibration associated with disturbance from an unpaved road without sacrificing road information generated by alignment torque.


Source: An EPS Control Strategy to Reduce Steering Vibration Associated with Disturbance from Road Wheels
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Old 8th December 2008, 14:20   #6
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Quote:
Originally Posted by alpha1 View Post
...EPS is just like toy steering system. There is absolutely no linkage between the wheels/suspensions and the steering wheels...
I think you are confusing EPS with Drive/Steer-By-Wire.

Sfilinto, dont worry about it. You will feel such vibrations almost as well even though your car has power steering.

cya
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Old 8th December 2008, 14:53   #7
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You are probably talking about steering problems. The manual steering column gets worn out pretty fast and you feel the bumps. The PS is a different setup.
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Old 8th December 2008, 17:23   #8
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Quote:
Originally Posted by Tejas@perioimpl View Post
There is no connection between the two. Power assistance is only for turning. You will get the same vibration feedback on your steering wheel.
Tejas, If this was true, the steering would not turn if the engine was switched off / electrical failure.
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Old 8th December 2008, 18:50   #9
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Quote:
Originally Posted by sfilinto View Post
Tejas, If this was true, the steering would not turn if the engine was switched off / electrical failure.
Exactly. It's power assistance and not total dependence. Try to turn the steering with car on and off and you will notice the difference. The steering will turn with engine off but not so easily. I used to have a safari and if the engine stalled while taking a turn, the steering would almost rip my arm off because it would violently swing back into straight position.

Last edited by Tejas@perioimpl : 8th December 2008 at 18:52.
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