Power steering electrohydraulic conversions

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File:HPU.JPG
New HPU

Introduction
This mod is for those who want to lose the parasitic losses from the power steering system while at speed but need to retain power steering function at low speeds and while in parking lots.

Hydraulic power requirements

Recirculating ball power steering boxes use lower pressure, from 700 to 1,200 psi.
Rack and pinion systems require slightly higher pressure, they tend to start at 1,000 to 1,100psi.
At idle the pumps for both systems provides between 2 to 4 gallons per minute.
At 5,000 RPM older Saginaw pumps can produce 20gpm.

Instructions for mod

There are 2 ways to do this mod.
1, Install a clutch on your power steering pump or get a hydraulic pump with clutch and install it on your accessory drive.
2, Install some kind of hydraulic power unit.
The hydraulic power unit can be a take off from another vehicle or an industrial hydraulic power unit for operating a snow plow or dump bed.

Clutched pump mod

Finding a clutch to fit an existing power steering pump has always proven to be very elusive.
Installing a hydraulic pump with clutch is a sure bet as long as you don't over pressurize the system. An industrial pump with clutch will have standard hydraulic fittings to connect them to a steering box or rack and pinion would not require a lot of creativity.
This is the most effective way to decouple your power steering pump from the engine drive. When the clutch is activated you have full use of the power steering system for an electrical cost of only 4 to 6 amps. But you have a belt running and a big old clutch spinning all the time.

Electric hydraulic power unit pump mod

This is where you remove you your original power steering pump and its belt and replace it with some kind of electric hydraulic power unit. Draw backs are:
Electric hydraulic power units use 50 to 200 amps of electrical power
You would need to wire in 6 gauge wire at a minimum to the motor wired through a solenoid
These units only provide about half the flow of a standard belt driven pump at idle
The benefits are:
When the Hydraulic power unit is off its not drawing any engine power
You can run the power steering during EOC
The electric hydraulic power units are relatively light weight
You can install them whereever you want

User experiences

Please enter your user name and any relevant data in the table

User data
User Name Car Make, Model, Year Cost of Mod Time to Perform Mod MPG Before Mod MPG After Mod MPG improvement guess Instruction Link
Example Data Saand Example Data Mazda, 626, 1991 Example Data $5 USD Example Data 1 Hour Example Data 27.2 Example Data 29.8 User mod detail or measurement detailed data
t vago 2001 Dodge Durango $350 2 Day 15.4 18.1 +18% EcoModder: Electrohydraulic Power Steering
t vago 2000 Dodge Dakota $300 1 Day 18.2 EcoModder: Electrohydraulic Power Steering

Problems / Consequences of mod

Hydraulic power units for trailer dump beds and electric power steering pumps built for small cars with rack and pinion only provide a fraction of the flow as compared to a pump found in an original equipment a recirculating ball system.

References

Forum thread links

Electric clutch power steering
Electric power steering pump conversion

External links

Hot Rod magazine; GM power steering serets
Hydraulic Store; Clutches for hydraulic PTOs
Saginaw power steering pump mods
\ Installing an electric power steering module

Related mods

http://ecomodder.com/wiki/index.php/Bigger_battery