[associates] Re: Back up steering systems

  • From: "Steve Townsend" <stownsend@xxxxxxxx>
  • To: "'associates@xxxxxxxxxxxxx'" <associates@xxxxxxxxxxxxx>
  • Date: Fri, 01 May 2009 09:09:58 -0600

Great forum! This is incredible for me, an evaluator in a small-population 
state--Utah--where I am doing driving equipment evaluations infrequently and 
still must be up on the issues.
 
Steve Townsend, M.A., OTR/L, ATP
Utah Center for Assistive Technology
1595 W 500 South
Salt Lake City, UT 84104
801-887-9532

>>> "Bradley, Eric" <E-Bradley@xxxxxxxxxxxxxxxx> 5/1/2009 8:52 AM >>>
Yes, the use of the backup pump is necessary. If not for the client, for 
everyone else on the road. If you have an individual that needs the maximum 
reduced effort steering and lets say the belt on the vehicle breaks, how is the 
individual going to steer/ control the vehicle?  Example: Lets say the belt 
breaks while on the  highway at 70mph and the highway is not divided. The 
individual using the maximum reduced effort steering is on the inside of a turn 
and you were on the outside of the turn traveling towards each other and their 
belt breaks. This individual is not going to be able to stay in their lane and 
are going to travel into your lane and create a head on collision. If this 
happened when both vehicles are doing 70 mph that would be at a closure rate of 
140mph. I do not know anyone that would like to be in that type of accident.
 
I also inspect quite a few vehicles and the only real problem I have seen is 
that when the power steering pump get a lot of miles on them the clearances in 
the pump get greater and the pressure and volume from the power steering pump 
decreases. If the pump gets weak enough it can/will turn the backup pump on. A 
thing to remember is that the only difference in reduced effort and zero effort 
steering is the amount of fluid flow allowed. More flow = less effort, less 
flow = more effort. 
 
The power steering cooler is a good idea, but may not really be necessary.  I 
run 75-100 lap events and run the engine at 7500 rpm and run no power steering 
cooler and have had zero steering failures. My race car has a steering system 
that you can adjust the feel/effort and the problem I run into is that when I 
put the maximum reduced effort valve. The power steering the pump can't keep up 
with the flow demands and the pump cavitates. When this happens the steering 
wheel becomes jerky and notchy feeling.  When the power steering pump cavitates 
the fluid flow stop/decrease and becomes Aerated. This will definitly heat the 
fluid and power steering pump as the fliud is not flowing over the parts 
cooling them as designed.  
 
 
Eric Bradley

From: associates-bounce@xxxxxxxxxxxxx [mailto:associates-bounce@xxxxxxxxxxxxx] 
On Behalf Of John Anschutz
Sent: Thursday, April 30, 2009 8:07 PM
To: associates@xxxxxxxxxxxxx 
Subject: [associates] Re: Back up steering systems

What a great topic.  I am not sure I know the answer.  I sometimes wonder if 
the backup pump is a backup for a problem that could be prevented.   I have a 
van with zero effort steering.   It suffers from stress due to over-heating of 
the steering fluid.   I think the original problem stemmed from two sources.   
1. If the engine is running and the Van is parked or at idle for an extended 
time with the wheels turned it will overheat the steering fluid.  2. Sometimes 
with new drivers or in an eval our evaluators want to really check out the 
client's turning abilities before ever going on the road.  Let me tell you that 
the rate of change in wheel direction with a Zero Effort (sorry I am old school 
- Maximum reduced effort) steering is far greater than what is typical in 
traditional steering.  It really heats up the oil.  Overheats.  The problem is 
that if the oil gets too hot seals can fail and you can have a lot of damage 
and you may have need for a back up system.    
Would a more modern approach be something like installing a steering fluid 
cooler like they do in some dirt track racing cars where they put great demands 
on steering?   I think DSI uses a cooler in their system.   Also, if we had a 
temperature monitor on the fluid then a dangerous or damaging situation could 
most likely be avoided all together.   If you can really do that then would you 
still need a backup pump?  Seems like the consumer would appreciate the ability 
to avoid major repair.   This is kind of like seeing that your car is 
overheating and you stop before you ruin the engine.   In this case the 
complicating factor is that steering is so much more important for safety to 
the consumer.  It would be nice if the consumer can avoid a problem and a 
failure of any kind.   Once you have a need for the backup you are back to oil 
squirting somewhere and you could have a fire situation that you mentioned.
Thanks again & I look forward to seeing other thoughts.
John Anschutz
Please don't anyone change there practices based on our discussion.  We are 
just brainstorming.


Please don't go out and change your practices based on these comments.  
On Apr 30, 2009, at 6:51 PM, cbckj@xxxxxxx wrote:



Thanks for a forum to discuss our issues.  It is really appreciated.  I am an 
inspector and have the unique opportunity to poke my head into, and around a 
lot of converted vehicles.  I am hoping to solicit opinions and guidance from 
this learned group of professionals, and to have some input into the general 
NMEDA community.  Please understand, I just want to stimulate some dialogue, 
not propose policy...case in point:
During inspections I have found that back up steering pumps are mounted in 
areas that are subject to damage even from minor impacts.  My concern is that 
these systems could rupture and leak with high pressure flammable fluids 
spraying into the engine compartment. The pumps are frequently mounted in the 
front bumper.  Back up steering systems have not changed in basic design for 
over 25 years.  One of my discussion points, (besides location change and 
design) is the actual need for these systems.  I have seen more problems with 
back up steering systems than I have heard reports that they serve their 
intended purpose.  The maintenance and installation issues are numerous.  Is 
the intended safety of this device worth the problems?  I'm  looking forward to 
your comments.
C. Kerry Jones
"The Space Between"
cbckj@xxxxxxx 

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