Rear Steer Thoughts

[simonr]

Shaun Stapley at POS makes a rear steer system with an auto park function, he also makes a kit with a mechanical "locked in straight ahead" mode for the US army if its of interest?

how about.... closed circuit rams mounted where the chasis end trailing arm bushes sit, (mid stroke being straight ahead) effectively increasing and decreasing the length of the trailing arms.. its an easier idea to build IMO, prox sensors can be mounted well out of harms way.

One could use electric linear actuators as trailing arms. The ones (Linak) I'm using for suspension adjust have a SWL of 6 ton which ought to be enough.

To disable my hydraulic rear steer I envision a pair of clips like bulldog clips that clip to the rod of the rear steer ram. You wind the ram to the left, put on left clip. Wind it as far as it will go to the right (fully compressing the left clip) leaving the right size gap for the right hand clip.

Neil, I agree with having a separate switch for centring - but that's effectively what I have. There are only two switches. On/Off and crab/normal steer. It just happens that the off position will centre the wheels as well as disabling the follow steer. Adding another switch which centres, just duplicates the on/off and thus gives one very little.

Si

[dollythelw]

nice idea but might be fun if you score the ram when the whole thing is covered in pooh?

how about a spring loaded drop in pin acting on a detent in a clevis? hold the pin back with a cable and when you want to lock off just release the cable and cycle the suspension until the pin locates - saves getting muddy

unsure about electric actuators though, silt, water and nastiness might make them unhappy, is that 6tonne SWL a load withstand or lifting capacity?

[muddy]

A lot of plant simply has a hasp type arrangement that just folds down over the switch to lock it in 2ws for the road, hell of a lot simpler than faffing around underneath.

[Anorak_Stan]

A lot of plant simply has a hasp type arrangement that just folds down over the switch to lock it in 2ws for the road, hell of a lot simpler than faffing around underneath.

Maybe, but I would think a Mechanical Locking System would persuade the MOT Tester that is was fully locked rather than a cover that goes over a switch !

Lyndon

[abezzina]

Hi, I'm new to this forum and looking for some info regarding rear steer self centering.I'm in the build phase of a challenge vehicle using Volvo portal axles with a PSC double ended ram at the front and single ended ram at the back.I am using a joy stick for the rear steering coupled to an electric driven hydraulic motor.Any info or circuit diagrams regarding RTC will be greatly appreciated.

Adrian

Malta

In my experience the biggest handicap with rear steer is not being able to get it straight again quickly enough after coming out of a turn.

Trialing in particular you need to be able to keep your eyes on the course and prepare for the next obstacle rather than be concentrating on some sort of indicator to see what the rear wheels are doing.

I built a circuit so that when the joystick was pushed forwards the rear wheels immediately returned to centre. It made a vast difference to the usability of the system.

[simonr]

Having built and run full servo with RTC, then a simple switched RTC (using switches to detect if it's off centre and using them to operate the valves to centre it) - I've come to a surprising conclusion!

I don't think it's necessary at all!

I have a steer position indicator in the cab which shows where the wheels are pointing but even with that, more often than not, I just look at the wheels.

Although it feels a bit odd at first if the truck is crabbing a bit, it makes no difference off road and you can soon fix it with a flick of the joystick / switch. I rarely used the RTC switch at all.

I think it's too tempting to try to use the rear steer all the time when in practice it' quicker to use the front steer and a couple of shunts.

After the initial novelty wore off, I now only use it when I need a bit of extra lock or to crab up a side slope for example - but most of the time leave it well alone. In odd circumstances, it's invaluable - but often it gets you into more trouble!

I now just use it (and the other 'toys') when I've run out of other options.

Some people have learned to use it seamlessly (Rob Tunnah springs to mind) but even for him it took a lot of practice. I have too much to think about with the regular controls and have found that by compartmentalising it in my mind for special circumstances - I get the benefits without the negatives.

When I get a chance, I'll draw you a simple wiring diagram for a switched RTC.

Si