Four Wheel Steering?

[boblynch]

What’s the latest news on four wheel steering? Since GM cancelled the Quadrasteer program it’s been quiet. The last concept rig I remember with 4-wheel steering was the Jeep Hurricane (see pics).

This technology would be very helpful to overland rigs. It would help heavy loads with or without trailers change lanes at highway speeds and dramatically reduce turning radius at slow speeds.

Are there any aftermarket options for this? Has anyone tried it?
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[sami]

http://www.autoblog.com/2005/02/18/cost-complexity-kills-quadrasteer/

http://www.trucktrend.com/features/consumer/163_0508_whale_watching/quadrasteer.html

Part of the problem was its limited availability. Quadrasteer-equipped trucks didn't have the big-block or diesel option boat and RV pullers require. Essentially a front Dana 60 axle swapped around, the Q-steer rearend can't cope with the torque output of the larger motors; buyers were left with a choice of engine grunt or maneuverability. Not surprisingly, people who tow chose grunt. When was the last time you heard turning circle come up when guys talk about their rigs?

 

[Lynn]

...It would help heavy loads with or without trailers change lanes at highway speeds and dramatically reduce turning radius at slow speeds.

I agree better slow-speed maneuverability would be nice, but I'm not too sure about high-speed lane changes.

Last I heard on the OctaMog they were trying to disable the rear steering at high speeds because it was too squirrelly.

Assuming you could independently control the rear steering, it would be a lot easier to parallel park a large rig! Or go around tight corners on small town streets.

 

[Lynn]

http://www.autoblog.com/2005/02/18/cost-complexity-kills-quadrasteer/

http://www.trucktrend.com/features/consumer/163_0508_whale_watching/quadrasteer.html

Don't monster trucks use Rockwell front ends swapped around for the rear steering? They can handle lotsa torque.

 

[olympiccop2002]

I think it's a great idea but wouldn't anyone be concerned about having two different steering systems to maintain? It can't be a simple system to work on that's for sure.

Bjorn

 

[boblynch]

During the last model year it was a $2K option (see Lynn's autoblog link). I would gladly pay for this option if it were in a truck I liked. I agree for ExPo applications the low speed benefits are great. However, from what I've read it also helps high speed lane changes (particularly w/ a trailer).

The point about adding more technology to service/maintain is a valid one. However, my mechnical skills are limited. Any major steering system problem is a tow truck call.

 

[milo12]

Dynatrac has rear steer axles available. They are controlled with an in cab hydraulic controller. They are not for high speed use. I think it would be a great addition to a large vehicle because it would significantly improve low speed maneuverability.

 

[Octamog]

The Octamog does have RWS. It utilizes a front Dana60 turned around backwards. There is a massive tie-rod (probably about 2" in O.D.) that runs the length of the chassis thru a set of pillow blocks and therefore directly ties the rear steering to the front.

The steering box is fairly quick (I think 4 turns L2L IIRC) which does make it a bit sensitive at freeway speeds. I'm working on a solution to selectively lock it out at speed. At low speeds, the turning radius makes the truck fun to drive -- it really turns heads when you pull into a typical 2-lane intersections and flip a U-turn without coming close to any curbs! It can turn curb-to-curb in 29 feet, and the inside wheels trace a circle 13 feet in diameter! This makes it have a tighter turning radius than a Honda Civic!

I have a video that showcases it's tight turning radius... I'll try and post it somewhere next weekend.

For now a couple of pictures of an Esarco on which Octamog is based:

Here you can see the steering rod directly above the far-side frame rail:

Another showing the steering rod on the right side:

 

[Ron B]

A really cool feature for sure. There are a couple guys who have done this to their hummers -- it's not very complicated with the irs. Here's a link to a video testing a recent 4wsteer hummer mod. You can see the computer control he uses at the beginning and some tight turns by 3:30.

http://www.youtube.com/watch?v=IR4Q3VzBKI0&feature=related

on a related topic, I often work with Chapman camera cranes that have 6 wheel steer. They are made from some amphibius vehicle from the 60's and uses 3 front axles. Here's a photo: