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Discussion Starter · #1 ·
Hi, I'm working on an off road project that uses full hydraulic steering with a double-ended ram.

I purchased a full kit from PSC Steering:

It needs a high-flow, high-pressure pump to run everything. The only pumps PSC makes are belt-driven. Does anyone have any recommendations on a good 12v motor that I could mount a pulley to and connect to the pump?

I'm not confident that any of the Electric steering pumps are going to be enough for this setup.

Thanks!

-Tristan
 

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Is this to be used on an EV or an ICE vehicle?
Experience with a similar issue at my work some years ago found that a 12v Mr2 Spyder steering pump took 70+ amps when trying to drive a large truck hydraulic steering box, and still was not a good match due to being designed for rack and pinion steering. It required a lot of 12v DCDC power.
The eventual fix was going to an oversized DC motor running from the EV traction pack and a steering pump from a truck equipped with a steering box. Not overly efficient but reliable.
 

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There are a lot of strings on here using Volvo pumps. Here’s one:
 

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Discussion Starter · #4 ·
Is this to be used on an EV or an ICE vehicle?
Experience with a similar issue at my work some years ago found that a 12v Mr2 Spyder steering pump took 70+ amps when trying to drive a large truck hydraulic steering box, and still was not a good match due to being designed for rack and pinion steering. It required a lot of 12v DCDC power.
The eventual fix was going to an oversized DC motor running from the EV traction pack and a steering pump from a truck equipped with a steering box. Not overly efficient but reliable.
It's for an EV project using a Nissan Leaf motor and inverter. I need full hydro steering because it will have 42" tall tires.
 

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Discussion Starter · #5 ·
There are a lot of strings on here using Volvo pumps. Here’s one:
I've looked into the Volvo pump. It seems like a good option for a more traditional steering setup with a regular steering box. From what I've read/heard it's not going to be enough for this type of setup.
 

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I would prepare for max current of 100A or more with those tires in some mud with a 12v motor.
The offroad vehicle I previously mentioned did not use a 12v battery to buffer for the high 12v steering demands so depending on your other loads, you should still be good to have dcdc converters in the 800W range with a decent sized 12v battery. Keeping with 12V may also have the benefit of a smaller motor due to less electrical insulation requirements in its design.
I am not an engineer though, just a guy with a DC clamp meter.
 

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Can you run 2 pumps paired together in parallel? Im not even sure if it'd work, or if there would be something weird like pressure flow from one pump back through the other, but surely it'd be possible? Maybe using some directional valves on the pump outputs?
Your power requirements would double for the motors, but if it gave you the ability to run 'off the shelf' oem parts, that would make sourcing any parts quite simple and well priced.
It would also give you some redundancy if one pump was to die while you were rock crawling somewhere
 

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Discussion Starter · #8 ·
I would prepare for max current of 100A or more with those tires in some mud with a 12v motor.
The offroad vehicle I previously mentioned did not use a 12v battery to buffer for the high 12v steering demands so depending on your other loads, you should still be good to have dcdc converters in the 800W range with a decent sized 12v battery. Keeping with 12V may also have the benefit of a smaller motor due to less electrical insulation requirements in its design.
I am not an engineer though, just a guy with a DC clamp meter.
I will have all the 12v stuff running off an Optima Yellow Top battery, which will be charged by a DCDC converter. I am concerned with the draw of another 12v motor, but lots of off roading involves sitting around and waiting. So I will have a switch to manually turn the pump off while not in motion.
 

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(y) for the switch to turn it off. Oversize your relay a bit to be safe.

Can you run 2 pumps paired together in parallel? Im not even sure if it'd work, or if there would be something weird like pressure flow from one pump back through the other, but surely it'd be possible? Maybe using some directional valves on the pump outputs?
Your power requirements would double for the motors, but if it gave you the ability to run 'off the shelf' oem parts, that would make sourcing any parts quite simple and well priced.
It would also give you some redundancy if one pump was to die while you were rock crawling somewhere
It sounds like his kit already has the pump that is sized for the demand. It looks more like a small hydraulic pump from an implement than a standard truck pump, so probably best to stick with it. That is if the black item in the top right of the supplier's picture is the pump.

Tristan, you would probably want to find out the recommended rpm range for that pump. Off road supply sites in my experience don't seem to have very technical datasheets.
 

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The older Model S AC compressors are HV and have a pwm controlled motor. I am not sure how feasible it would be to modify (take the pump section off and replace with a pulley) or if the specs are anywhere near correct, though.
 

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I am using a Volvo 12v PS pump on my Land Cruiser and planning on 35s. Maybe I will need to upgrade from the sounds of it. No mud around here just rocks. The Volvo pump can be controlled with CAN messages to increase the pump speed when under loads also it runs at about 60% power otherwise.
 

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Discussion Starter · #12 ·
I am using a Volvo 12v PS pump on my Land Cruiser and planning on 35s. Maybe I will need to upgrade from the sounds of it. No mud around here just rocks. The Volvo pump can be controlled with CAN messages to increase the pump speed when under loads also it runs at about 60% power otherwise.
From what I’ve heard that pump will probably be fine for that application.
 

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Perhaps I was under a false understanding that the issues I witnessed with a pump from a rack-n-pinion car used on a steering box truck were due to design incompatibility, when maybe either the flow and/or pressure just weren't enough.
ELC: your build thread is a bit long and I haven't made my way thru it yet, have you run your steering at all yet with wheels on the ground? (Curiosity from one land cruiser owner to another)
 

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Perhaps I was under a false understanding that the issues I witnessed with a pump from a rack-n-pinion car used on a steering box truck were due to design incompatibility, when maybe either the flow and/or pressure just weren't enough.
ELC: your build thread is a bit long and I haven't made my way thru it yet, have you run your steering at all yet with wheels on the ground? (Curiosity from one land cruiser owner to another)
Not yet I am waiting on some fittings in the mail then I will plumb it up. I'm just hoping that the flow and pressure will be "about right" but I have nothing to really go on other than both the Volvo and Land Cruiser being fairly modern vehicles with the same size lines and fittings.
 

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ELC: Hope the Volvo pump works for you. If not you could probably use it for some other hydraulic attachment for your truck.

Tristan: you do have the pump for your kit, correct?
Can the supplier offer any more info for its speed requirements, or should we start counting rotation ratios on our crankshafts and pump pullies?
 

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Hi, I'm working on an off road project that uses full hydraulic steering with a double-ended ram.

I purchased a full kit from PSC Steering:

It needs a high-flow, high-pressure pump to run everything. The only pumps PSC makes are belt-driven. Does anyone have any recommendations on a good 12v motor that I could mount a pulley to and connect to the pump?

I'm not confident that any of the Electric steering pumps are going to be enough for this setup.

Thanks!

-Tristan
Be warned that any motor larger than those found on electric steering pumps will absolutely destroy range if it's a pure EV. JerryRigEverything 's episode on his hummer braking system discovered this after I told him the same thing and gave him links to utilizing the tesla hardware.
 

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Not if its speed and current are controlled. Then it's just added weight & space for a minor range hit.

That's the beauty of using a controlled motor vs just plugging one in and dumping excess flow & pressure overboard. You can tune it. And once you tune it, you can log its usage, and go back and retrofit the motor if you're building a bunch of machines.

Noisy, but @Tristan probably doesn't care
 

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Discussion Starter · #18 ·
I actually want to keep it as quiet as possible--seems like a big advantage of EV. :)

I just got one of the new electric steering pumps that come in Jeep Gladiators to think it was in a Gladiator last night by spoofing CAN signals, so I'm going to try to have some hoses made for that this week and see how well it works.

It's relatively compact and surprisingly quiet:

 

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Hi all,
I am new to this forum and just back reading a few threads. I am considering starting a EV project but I am not going to lift a spanner until I have the whole of my parts bin fully understood not just from a technical performance point of view but also, and to me most importantly, from an electrical control point of view. There seems little point buying components if they can not be controlled efficiently.

This thread has taken a few twists and turns it stated as a open question on control of the Volvo EPHAS in 2020 and now appears to be a wider topic of different pump solutions.

Volvo EPHAS
There was a great technical document posted on day one (attached). It covers in good detail the hydraulic flow, the CAN comms, current / rpm data, fault behaviour and failure modes. See page 8 -14
In summary there are great advances of getting this pump to work correctly, but it is a full CAN module with many inputs from many modules. There is another concerning issue over and about the CAN massage issue which aren't insignificant. There is a handshake ID between the CEM (central electronic module) and EPHAS, it this isn't seen EPHAS shuts down into fault mode - runs at approx 70%.

Is the Volvo the best unit to use bearing in mind the control difficulties? I can see it is an ideal replacement for a engine driven mechanical PAS pump, and aside from pressure balance / tuning issues it is a good solution with little mechanical upset elsewhere it the vehicle. But without full control of the pump motor tuning is hard.

Does anyone have any thought of column or rack mounted electrical motor based power steering systems?
Nissan have a column mounted electric motor based system with a stand alone ECU. Much more mechanical integration but once the cutting, shutting and welding is done it will work electrically.
Nissan car stuff is clearly not big enough for the bigger vehicle but maybe there are more stand alone systems out there?
 

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Some people use those. Requires both room and a fair amount of butchery.

An EPHAS boils down to a mounting bracket with the pump anywhere it'll fit and a bit of plumbing. The mechanical integrity of the column or rack/box is not messed with.

Good to see you contributing as probably the most knowledgeable in CAN member. Welcome.
 
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