4 wheel steer GP

1940 - 1941 BRC, MA, GP, Preproduction Prototypes. Knowledge Base NO EBAY or COMMERCIAL SALES.
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acmack
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Re: 4 wheel steer GP

Post by acmack » Sat Jan 23, 2010 7:19 pm

I am very much a novice when it comes to GP's and even more so when it comes to 4WS's BUT I was led to believe that the rear steering axle turned at a shallower turn arc than the front on GP's to minimize the rollover tendency. Having said that, the rear axle here seems to have a very extreme turn arc relative to the front axle turn arc.
Is it "out of adjustment" or does it look correct to those folks who really know the GP 4WS? David
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Re: 4 wheel steer GP

Post by Rory Grenier » Sat Jan 23, 2010 7:25 pm

David,
I was looking at that also!!!! It looks like our 4WS Versahandler at work.

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Re: 4 wheel steer GP

Post by Michael Browne » Sat Jan 23, 2010 11:06 pm

Hello David,

The 4WS GP 'second' steering box works on delaying the movement of the rear wheels.

To explain in more detail, the 4WS front wheels steer with the steering wheel the same as the 2 WS GP however the rear wheels don't start to turn until the steering reaches about 7deg of movement at the front and then they continue to move at a faster rate than the front until full cramp is reached front & rear.. This is achieved by delayed action cam in the secondary steering box near the rear axle and different length pitman arms.

Delayed 4WS make for more stable driving at speed. 8)

The Bantam 4WS worked by moving the front and back wheels at the same time and was very twitchy.
Michael Browne

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Re: 4 wheel steer GP

Post by 41jeeps » Sat Jan 23, 2010 11:24 pm

Michael Browne wrote:Hello David,

The 4WS GP 'second' steering box works on delaying the movement of the rear wheels.

To explain in more detail, the 4WS front wheels steer with the steering wheel the same as the 2 WS GP however the rear wheels don't start to turn until the steering reaches about 7deg of movement at the front and then they continue to move at a faster rate than the front until full cramp is reached front & rear.. This is achieved by delayed action cam in the secondary steering box near the rear axle and different length pitman arms.

Delayed 4WS make for more stable driving at speed. 8)

The Bantam 4WS worked by moving the front and back wheels at the same time and was very twitchy.

Michael said it all.
P7053024.jpg
gp 4ws box
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P7053056.jpg
4ws steering box pitman arms
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P7053055.jpg
4ws pitman double rod
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Re: 4 wheel steer GP

Post by Fred Ransome » Sun Jan 24, 2010 5:29 am

Thank you for the gearbox photos. Now I can do a proper verification. I was told the rear steering delay was implemented because parking a 4WS vehicle alongside a curb was very difficult. When te driver would turn the front wheels to pull out the rear end of the Jeep would jump the curb onto the sidewalk. Putting in the delay prevents this tendency. Guess those engineers in the old days knew what they were doing even if they didn't have computers. :wink:
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Re: 4 wheel steer GP

Post by acmack » Sun Jan 24, 2010 8:47 am

4WS was not a new concept in the 40's nor was it new to U.S. military vehicles in the 40's. The Jeffery Quad had 4WS back in the mid teens, before WWI.
But 2 things happened since those pre-WWI lessons; 1- cars and trucks drove faster and 2 - lessons were forgotten and had to be relearned. David
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Re: 4 wheel steer GP

Post by 41jeeps » Sun Jan 24, 2010 10:38 am

The delay in the rear steering is 100% for high speed use.
The "outbreak" from the rear is something an unfamiliar driver has to pay attention for when parking.
The 4WS GP handles exactly the same as a 2WS at high speeds.
If some weight is in the back, it becomes much more unstable.
I think that is because the lean from the jeep somehow moves the rear wheels I guess.

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Re: 4 wheel steer GP

Post by acmack » Sun Jan 24, 2010 5:20 pm

Here is a wartime photo of a 4WS. Notice the front wheels are at the maximum turn angle. Now notice the shallower angle of the rear axle as would be expected.
The prior "cell phone 4WS" does not appear to have the front wheels quite at the full turn position yet the rears are at a greater turn angle.
David

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Re: 4 wheel steer GP

Post by 41jeeps » Sun Jan 24, 2010 11:50 pm

This is full deflection.
DSC04644.jpg
GP rear wh angle 1
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DSC04647.jpg
GP rear wh angle 2
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Re: 4 wheel steer GP

Post by Jim Gilmore » Mon Jan 25, 2010 6:20 pm

David,

I finally found a snapshot of my 4 WS GP when I brought it home many years ago.

Jim Gilmore

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Re: 4 wheel steer GP

Post by 41jeeps » Mon Jan 25, 2010 11:57 pm

Jim, that's a cool GP 8)
I like the hard top...did you kept it as is or did you already dismantled it ?

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Re: 4 wheel steer GP

Post by DavidA » Tue Jan 26, 2010 12:23 am

Great find, good photo and wow. Thanks for posting. :D

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Re: 4 wheel steer GP

Post by Rory Grenier » Tue Jan 26, 2010 5:05 am

Jim,
It Looks great !!!!! Did it have the correct matching motor ?

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Re: 4 wheel steer GP

Post by mr rusty » Tue Jan 26, 2010 2:50 pm

Hi Jim,

Thanks for posting the pic, looks a real corker, and so complete. Would be good to see a pic of what it looks like now.
Peter

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Re: 4 wheel steer GP

Post by acmack » Tue Jan 26, 2010 6:09 pm

Beautiful! I hope it's in your restoration shop now getting ready for this summer's show season! David
Any other spacecraft or missile owners out there?
MAR 43' GPA 9545 MAR 43' GPA 10568 getting there!
60' M422 538
65' Apollo BP CM A-36
60' Gemini BP CM MSC312

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