Can we design an A frame that all would agree is legal?

Jul 29, 2007
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Hi I haven't been involved in the discussion, but I have been thinking about ways to make certain aspects legal. One is the inability to reverse under control, one way to achieve this is for the front wheels to be lifted clear of the ground by some means.

The actual "A" frame could be used for this if the mounting points on the car were strong enough to support the weight of the front of the car, and if your tow hitch could support a downforce of about 500kg. Then using a hydraulic ram fitted under or above the hitch with the other end connected near to the opposite end of the "A" frame, you could lift the front wheels clear of the ground turning it in to a two wheeled trailer, which can be reversed under control. The hydraulic power could be supplied locally or from the steering pump.

Olley
 

Road Runner

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My A frame has a Jockey wheel fitted so if a problem does occur you can quickly unhitch the vehicle and drive it where needed using the jockey wheel.

MHfun rally goers have seen it in action.

I had to do this when at the tunnel when they expected me to do a tight U turn onto the train that the bus couldn't do in one go anyway:RollEyes::Doh:I should have been with the HGV's as I was longer than most of them.

To be honest you cant see your toad properly when reversing anyway so this is your safest option :winky:
 
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Jim

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This thread has spent the best part of today "closed" that was a mistake, please do post here. If we can invent an A frame that everyone deems is legal well.. ££$$.....


This time next year Rodney.....:ROFLMAO:
 

Tony Santara

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Hi Olley
the power to lift a car would be quite a lot i would imagine going off the effort it takes to jack up a car
I think the better way would be to look at some device that could be fitted to steering to make that turn accordingly when reversing

Trouble is i don't know what yet :RollEyes:
 

American Dream

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Would be a problem with the normal power steering cars.

No prob with rack and pinion types as far as I can see.

The steering lock would need to be disabled though .:ROFLMAO:

How many cars come without power steering now ?

A pair of idler wheels that lower when reversing?
 
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Tony Santara

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Would be a problem with the normal power steering cars.

No prob with rack and pinion types as far as I can see.

The steering lock would need to be disabled though .:ROFLMAO:

How many cars come without power steering now ?

A pair of idler wheels that lower when reversing?
good one Steve how would you power them and on what would you mount them ?
 

Road Runner

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Recovery only John
Try again mate :thumb:
You caught me there Tony I had not put down what i actually meant:RollEyes: (sorry for the edit in between:RollEyes::Blush:)

I have had tilt/slide recovery lorries with extending spectacle frame for recovery for :winky:

Got nicked:Doh:
 

American Dream

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Power via an integral Fluid pump.

Just a thought.

My Smart car had an electrically powered brake servo pump.Use a 12v Hydraulic Pump. Fit a large capacity Hydraulic fluid reservoir.

Couple that to a pair of hydraulic rams to provide lift with Upper and lower extremity safety switches and appropriate warning light/reversing siren, lamp on dash and...........

Oh Well Just a thought.:Doh:
 
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Road Runner

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How about a robot innit steering it mimicking the bus driver?

Suppose you'll still have to rely on the dummy to reverse though:roflmto:
 

Tony Santara

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Steve
Could they not be powered electricaly to keep it simple
fluid reser and hyd pumps sound a bit heavey

But hey we're thinking :thumb::thumb:
 

Road Runner

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The mind boggles how this is going to be safe.

I'll stick to my braked A frame for now.
 

American Dream

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Steve
Could they not be powered electricaly to keep it simple
fluid reser and hyd pumps sound a bit heavey

But hey we're thinking :thumb::thumb:
Hi Tony.

I did mean a 12v Hydraulic pump.

I don't think it would be very heavy at all.

The rams might weigh the same as a couple of motorcycle Rear Shockers.

The mech would be integral to the frame and the additional electrical connections would be via an extra connector to the van's electrical system via fuses etc.

eg Sealed hydraulic system.
 
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Tony Santara

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Got you Steve

I was thinking along the lines of electric motor thru some kind of gearing on an arm
trying to think along the lines of van tail lift operation

any way i'll have to sleep on it up at 4 am for work

BTW Olley's gone quiet is he still thinking :roflmto::roflmto:
 
OP
olley
Jul 29, 2007
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Hi Olley
the power to lift a car would be quite a lot i would imagine going off the effort it takes to jack up a car
I think the better way would be to look at some device that could be fitted to steering to make that turn accordingly when reversing

Trouble is i don't know what yet :RollEyes:
If a hydraulic ram has a surface area of 1" and you have oil at 1000psi that's 1000lbs that ram can exert, enough to lift the front of a small car.
Remember many RV's including mine have jacks capable of lifting the entire RV clear of the ground.

You could also use a caster wheel on a leg, again hydraulically powered to lift the front clear, if the pivot was the same as the "A" frame mounting points on the car then no strengthening mods would be needed on the towing car.

Either of these or other ideas could be energised by a relay powered from the reversing light.

This is only going to be used when reversing so safety shouldn't be an issue.

Olley
 

wildcamper

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hi would it be possible for someone to come up with a cheaper spec lift that could be mounted under the back kind of a slide in and out when needed???
 
G

GeorgeTelford

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Bear in mind the see saw / leverage effect of a motorhomes rear overhang....

Check out the nose weight allowed, this would be circa 50Kg to 75kg on a car maybe 125 on a short overhang 4X4, not looked but would guess it would be low side for a motorhome....with the large overhang on many motorhomes, I do not think that lifting the best part of 500Kg off the ground is going to be viable.

If you look at tow trucks they have minimal rear overhang to keep the downforce on a very short lever at the rear and the counterweight (front end is long lever)
 
G

GeorgeTelford

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PS the downforce of a 500 Kg car weight on nose, based on a 60% overhang it would require 750kg counter to regain equilibrium, it would generally overload rear axle and make the front end light, which would effect steering badly, on a pusher it would be even worse...

The Aframe is an ideal solution to the above problem, minimal noseweight....
 
OP
olley
Jul 29, 2007
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Have to agree with George, the idea of hanging 1 tonne of the back of my RV is a non-starter. Even my first idea for using a ram to lift to lift the front wheels clear would probably overload the rear axle, but the very short distances and slow speeds when reversing wouldn't make this a problem

Been thinking about the various ideas for lifting the front wheels clear, they would all make the "A" frame very heavy, so why not reverse it? put the ball hitch on the car and permanently fix the other end to the RV. Then when not in use it would simply fold up flat against the back.

Olley
 

Road Runner

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Interestingly enough have you searched through the goodies the yanks make up to hang on the rear hooks:Eeek:do a google search.

Mind you most are raving as lots just tug on an unbrakes frames and mainly 4 x 4's as well:Doh:

It's not big and it's not clever:Doh:



=====================================================

Mind you here one of their other ideas (what is going on with those wheels though?)

http://www.campingworld.com/browse/products/index.cfm/Outdoor-and-RV-Accessories/Tow-Center-Of-America/Hitching--Towing/Roadmaster-Tow-Dolly/prodID=1683

mind you that's illegal here

maybe their buses are not fit for purpose too?


====================================================


BTW:- guys so of your suggestions are super but at what cost?
 
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Geo

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The solution is staring you in the face:cry:



Change the Law:thumb:
Geo
 

Road Runner

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View attachment 379 How about one of these with a tow receiver at the rear of it and tow it backward with the rear wheel off the ground.



I.E. design a cheap car fit for purpose to be tugged? rather than a complicated frame?
 
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OP
olley
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Hi John, not fit for purpose, as they say. ::bigsmile: mate of mine had one, the amount of times I had to push start it to get to work, and scary to drive.:Eeek:

Olley
 

Road Runner

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Hi John, not fit for purpose, as they say. ::bigsmile: mate of mine had one, the amount of times I had to push start it to get to work, and scary to drive.:Eeek:

Olley
I liked on roundabouts when you had to start accelerating before the actual gap became free:Doh:
 
F

fordy

Deleted User
The solution is staring you in the face:cry:



Change the Law:thumb:
Geo
Sounds good to me how would we start maybe GT could let us know the best way to do it ?

FORDY:Smile:
 
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