Electric power steering pump conversion

[me and my metro]

I have to ask, how are you powering your hydra boost brake booster? Did you go to a vacuum booster and an electric vacuum pump? I may have missed that thread. How much power does it take to push over relief on that p/s pump? I wonder if you have looked at an electric solenoid to bypass the system except when you need power assist.

[oil pan 4]

I am not using hydro boost.
From what I can tell the power steering pump by passes through the inside of the steering box when you don't need it. Only developing something like 150psi, but that pump generates so much flow it still soaks up a lot of power.
I found that it took 200 watts at idle speed to turn the power steering pump when its "bypassing" but it took over 500 watts at 2000rpm.

Plus in my infinite wisdom I ordered the wrong pump. Its only rated at 0.35 gpm. Not even worth trying. I knew something wasn't right when that pump showed up with size 4 ports.
I think what I really need is a single acting hydraulic power unit. I think bailey hydraulics has the perfect one, 2.1gpm, internal relief set for 1,400psi and normal -6 OR ports.
I don't have to have the "single acting" capability. This will allow me to turn off the pump and energize the single acting solenoid that will instantly form a bypass around the pump. It may make turning the wheel easier with no hydraulic power.

[Gasoline Fumes]

What about just running the original pump with an electric motor? Are these hydraulic power units more efficient?

[oil pan 4]

It would take a large 1/2 to 3/4 horsepower 12v DC motor that costs around $300 and weigh around 30lb.
I believe the Saginaw P1 is just too large to be coupled with a fractional HP DC motor up under the hot engine compartment. The motor would constantly be running in overload in a hot environment so it would just fry.

The entire hydraulic power unit weighs about 30lb and I can put it where ever I want.

[oil pan 4]

HPU came in today.


It has a 3 gallon hydraulic tank. Which is about 3 gallons more than it needs to have.
I will cut it down as short as possible, weld it back together making the tank between 6 and 7 inches long.

Shipping weight was 36lb. With out all the packaging, smaller tank I think it will be closer to 30.

[oil pan 4]

I finely got around to testing my hydraulic power unit in my power steering application.
The bad new is it draws more power at idle than I expected, I was expecting 40 amps, it draws 60 amps.
The good news is turning the steering wheel side to side on dirt it was drawing less than 110 amps. I was expecting it to draw closer to 200.
The steering wheel was turning almost effortlessly.
So 2.1GMP at 1400psi is more than enough.

The power steering pump still has that huge 3 gallon tank on it. I wanted to test it before I spent the time cutting it down and welding it back together.

[oil pan 4]

The best thing I can think of to control the power steering is put it on a manual momentary switch wired to a time delay off relay that gives me between I am thinking 10 and 20 seconds of power steering per push of the switch.
Then place the switch on the center console so I can hold it down continuously if needed.

Driving the 3/4 ton suburban with power steering disconnected I have found that I don't need it most of the time. Backing up the trailer I will most certainly need it.

I believe the duty cycle of the hydraulic power unit is 2 to 3 minutes on, 8 to 10 minutes off. Depending on the load, temperature, ect.

[oil pan 4]

I cut the 3 gallon tank down to about a 2 quart tank.

[deejaaa]

with a smaller tank, it might need an inline cooler.
momentary switch: connect a momentary and an on/off just in case it's needed for a longer period.

[oil pan 4]

If anything it might need a fluid warmer. I expect the pump to be off all most all of the time.
I was thinking that I would wire it into a time off relay. So I have 10 seconds from the time I release the button.