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Ram-assist calamity!


simonr
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Yesterday, I had plumbed in my ram assist using a steering pump from a BMW 7 series. I'm actually using a S**uki V***ra steering box - so the first bit doesn't necessarily apply to Landy boxes.

Anyway - the increased pressure has blown the input seal and cracked the piston casing in the steering box. I'm going to go back to the original pump and a new box c/o RogueVogue.

The original pump does not produce nearly enough flow to run the PAS and ram assist - and it seems that the valve ports in the box are not big enough anyway.

What is the solution?

What about connecting into the steering box as if you were going to fit ram assist, but instead fit a couple of pressure switches.

When the pressure in one end or the other goes over a certain value, it switches on an electric PAS pump to drive the ram.

This would give you a 'dead band' where you are only using the original PAS - but when you put enough force into the steering wheel, the electric assist kicks in.

That should give you more 'feel' in the steering while the steering forces are low - but above that give you additional assistance.

Unlike traditional ram assist it will not change the speed of your steering - and potentially you can switch the whole thing off after which, it will just act as a steering damper.

Can you see any gaping holes in my thinking?

Si

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Yesterday, I had plumbed in my ram assist using a steering pump from a BMW 7 series. I'm actually using a S**uki V***ra steering box - so the first bit doesn't necessarily apply to Landy boxes.

Anyway - the increased pressure has blown the input seal and cracked the piston casing in the steering box. I'm going to go back to the original pump and a new box c/o RogueVogue.

The original pump does not produce nearly enough flow to run the PAS and ram assist - and it seems that the valve ports in the box are not big enough anyway.

What is the solution?

What about connecting into the steering box as if you were going to fit ram assist, but instead fit a couple of pressure switches.

When the pressure in one end or the other goes over a certain value, it switches on an electric PAS pump to drive the ram.

This would give you a 'dead band' where you are only using the original PAS - but when you put enough force into the steering wheel, the electric assist kicks in.

That should give you more 'feel' in the steering while the steering forces are low - but above that give you additional assistance.

Unlike traditional ram assist it will not change the speed of your steering - and potentially you can switch the whole thing off after which, it will just act as a steering damper.

Can you see any gaping holes in my thinking?

Si

sounds good. definately worth a try

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What about connecting into the steering box as if you were going to fit ram assist, but instead fit a couple of pressure switches.

When the pressure in one end or the other goes over a certain value, it switches on an electric PAS pump to drive the ram.

Can you see any gaping holes in my thinking?

I assume it would take a man sized motor and another steering pump? This would be quite heavy - part of the Suzuki thing is the lightness.

Chris

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I'm not sure your electric pump idea would react quickly enough on a steering application. To overcome this sort of problem on other hydraulic systems, an accumulator is used, basically a rechargeable reservoir of pressurised fluid ready to be released when needed, in much the same way as you'd be switching on your electric pump, done by hydraulic circuit though. It will all start getting a bit "pipey" but will work well.

To keep things simple could you not retain the BMW pump with its higher flow but modify it to reduce the pressure?

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I'm not sure your electric pump idea would react quickly enough on a steering application. To overcome this sort of problem on other hydraulic systems, an accumulator is used, basically a rechargeable reservoir of pressurised fluid ready to be released when needed, in much the same way as you'd be switching on your electric pump, done by hydraulic circuit though. It will all start getting a bit "pipey" but will work well.

To keep things simple could you not retain the BMW pump with its higher flow but modify it to reduce the pressure?

Or just put pressure reduction in the line to the steering box. That way you have the full power of the new pump without blowing away the Vit steering box.

Steve

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Lack of flow through the steering box is not just a suzuki thing. The LR box also suffers the same. With a decent size ram it does slow the steering. My ZF pump produces plenty of flow but the box will not pass it fast enough so theres definatly an issue that needs some work here. The ability to have weighted steering for feel but the assist as requred would be perfect. Sounds like your on to something here Simon. The pump response shouldn't be an issue, They run electric pumps on many modern cars. The valving and pressure switch side of things would just be basic hydraulics and I assume some trial and error to get the pressure settings right. I Have been looking into the whole steering thing a lot recently. There are fantastic systems available but all cost ££££££££'s and need a specialist box which Im not keen on, I always tryy to keep things so a std part can be fitted if need be to finnish an event. This sounds very very promising Simon. I'm very interested.

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Hi flow pump + Sweet steering control valve + manual steering box (choose a ratio and flavour to suit you) + 2.5" OD Double acting ram mounted to axle = light, strong steering that's as fast as you like. The steering control unit is used on Howe's trophy truck Q/R steering racks and will flow enough fluid to not limit the speed even when using a 3" OD ram. The overall cost of the system is no more than a decent full hydro system (a full hydro control unit (aka orbital valve) and a PAS steering control valve cost pretty much the same).

Oh, and you'll have to bin the LR ball joints as they'll die pretty much straight away :P

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Lack of flow through the steering box is not just a suzuki thing. The LR box also suffers the same.

That was really the point. (Well done Steve - have a House Point ;) )

As has been mentioned, there are a lot of cars with electric/hydraulic PAS. The hydraulic pump assemblies seem to contain everything needed - and are pretty light and small.

The nice thing is they will operate in addition to your existing steering - so only needs the capacity to cope with the volume of the ram, not the box and ram.

I agree that I could put a variable pressure relief if the system I have and it would fix it - but still the flow through the valving in the box is very limited.

Will's solution is fine - but still expensive compared to something mostly made of scrap like this! Something else I wondered about was using the torque sensor from an electric PAS system and using that to control the valving on a ram. Trouble was that the output of the torque sensors is difficult to read without a computer - which is when the pressure switch thing occurred to me!

Si

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Not 100% sure, but is a full hydro system legal in the UK?

I thought that we could only use PAS?

You are correct - but that's not what this is. It's just a means of leveraging the force generated by the PAS without limiting the steering speed.

I did actually have another - simpler idea.

Instead of a solenoid valve, use a pilot operated valve (a valve that uses hydraulic pressure to operate the valve - often used to multiply pressure or flow). This avoids any electrickery and can use the pressure in the PAS box to switch a much higher flow valve.

Si

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You are correct - but that's not what this is. It's just a means of leveraging the force generated by the PAS without limiting the steering speed.

I did actually have another - simpler idea.

Instead of a solenoid valve, use a pilot operated valve (a valve that uses hydraulic pressure to operate the valve - often used to multiply pressure or flow). This avoids any electrickery and can use the pressure in the PAS box to switch a much higher flow valve.

Si

Hi Simon

Have you thought of using a columb assist unit so you help with the effort required to turn the box ? I was talking to an engineer at Adwest a few months back and this is what they are just looking at doing.I have been working with a electric hydralic pump set up for a while now, but with a double acting ram for rear steer and you can get very good response from an electric pumped unit without any delay.

Jon

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Hi Simon

Have you thought of using a columb assist unit so you help with the effort required to turn the box ? I was talking to an engineer at Adwest a few months back and this is what they are just looking at doing.I have been working with a electric hydralic pump set up for a while now, but with a double acting ram for rear steer and you can get very good response from an electric pumped unit without any delay.

Jon

Jon, part of the issue is that a LR steering box was never designed to work with 35" plus tyres with big off set - they are not really up to the abuse many subject them to off road. The weight of the steering is only one issue....

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Jon, part of the issue is that a LR steering box was never designed to work with 35" plus tyres with big off set - they are not really up to the abuse many subject them to off road. The weight of the steering is only one issue....

Hi Will

I have one of Adwests all signing and dancing steering boxes on my RR with 2.5 turns lock to lock and is very lightly valved so I have full assistance at any speed and I have done away with the standard steel bypass pipe and gone to slightly oversized Aeroquip, and the ZF pump has been drilled out to give better flow this seems to work ok with 37/14.5 creepy crawlers. It was lighter when running std ratio gears. I still find i can "stall" the steering when stood on its nose and trying to steer ,but this rare now.

Jon

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What about the sector shaft??? They have a habit of shearing....

Also, are you still running Rover track rod ends?

Disco 2 H/D sector shaft and still on std type trackrod ends ,I have got (but not fitted yet ) rose joints with rubber covers to stop crud getting in. :)

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ive been thinking about this after being stood on my nose and not being able to steer at all and that was only on aired down 35's.

what about a manual steering box but in the steering linkage have an orbital valve but with a shaft running right through so you still retain your 'mechanical link' . them just have one of the high volume/ pressure pumps and a double acting ram that also goes in the middle of your drag link on the back of the axle so still retaining your 'mechanical link' should it dump its fluid.

excuse pictures but hope it helps.

post-8713-1237462566_thumb.jpg

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ive been thinking about this after being stood on my nose and not being able to steer at all and that was only on aired down 35's.

what about a manual steering box but in the steering linkage have an orbital valve but with a shaft running right through so you still retain your 'mechanical link' . them just have one of the high volume/ pressure pumps and a double acting ram that also goes in the middle of your drag link on the back of the axle so still retaining your 'mechanical link' should it dump its fluid.

excuse pictures but hope it helps.

post-8713-1237462566_thumb.jpg

Hi I can see what you want to achieve but when the system is not active you would be trying to move not only the std steering but the oil in the hydralic oil in the ram too, It's going to be a tricky one to get round. The single acting ram to assist the original Pas is the way to go , IF you can make the steering box strong enough to cope with the extreme loads that hydralics can dish out.

Jon

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Hi I can see what you want to achieve but when the system is not active you would be trying to move not only the std steering but the oil in the hydralic oil in the ram too, It's going to be a tricky one to get round. The single acting ram to assist the original Pas is the way to go , IF you can make the steering box strong enough to cope with the extreme loads that hydralics can dish out.

Jon

the only thing is this way eliminates the slow steering problem because the steering box is not trying to move all that fluid through it. the point about moving all the fluid when the system fails i dont think is that much of an issue as its only as an emergancy back up. and also if you loose all your fluid the ram system would in effect become disconnected from the manual system.

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Hi I can see what you want to achieve but when the system is not active you would be trying to move not only the std steering but the oil in the hydraulic oil in the ram too, It's going to be a tricky one to get round. The single acting ram to assist the original Pas is the way to go , IF you can make the steering box strong enough to cope with the extreme loads that hydraulic can dish out.

Jon

Rather than shut it down when not required could you just reduce the pressure to a point that just overcomes the issue of trying to move the rams.

Steve

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What about putting an orbital valve inline with a quick diconnect lower columb that can be reconnected for road sections? My rear steering is electric over hydralic on road sections I have dead mans valves to lock off the hydralics ,even though I turn the power off to the pump.

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I'm no hydro expert, but when I put a bigger steering pump on for my milemarker and standard steering I added a relief valve to protect the box from the higher pressures.

Following simons cunning plan to use solenoids/valves as the control for the ram with a 2nd pump powering that. Could you not use the blown off pressure of the the more high power pump to run the ram instead of having a second pump?

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yeah that sounds good , where's the best place to get a pump and orbital valve. i'll have to modyfy the valve so the shaft continues out of the bottom end but it souns like a plan.

I got my hydro bits direct from psc motorsport in the states a few years back, but tractors and loaders use the same orbital valve as for the pump I got one from a commercial vehicle breakers that was used to lower the front of buses for people to get in easier and it came with flow control valves and two 10" stroke rams all for £75.

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J999dpt - how do you plan on balancing the hydraulic and mechanical part of the steering? Even if you can get the turns to lock to match the ram is turning linear motion into rotary motion and the mechanical system is all rotary so the movement won't be balanced. This was the reason I ditched this idea and looked for another solution. The way a PAS steering valve and a hydraulic steering control valve work are very different!

Like you I wanted to remove the issue of the Rover PAS box which isn't up to what we want to do to it. Even with the sort of work Simexslave has had done you don't get that much steering force (and if you did then you'd just break LR TREs) and modifying them for hydro assist only has reasonable results - you can't flow enough fluid at a high enough pressure IMHO. I ditched the idea of going to Howe for a system like filthyboy's because it was very expensive and required the steering box be sent back and forth across the pond to get it set up. After a few nights of research I came across the Sweet steering valve and concluded they were ideal for the job - this is essentially a bigger, stronger version of the valve in the top of your PAS box but is remote mounted. This will take high fluid pressures and will flow fast enough to move a 3" OD ram as quick as the driver can steer on trophy trucks linked up with a quick ratio steering rack. Oh, and Rakeway sell them too so they're easy to get hold of B)

HTHs

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