suspension..... air, rubber, leafs, or coils ?

[Renze]

As some might remember, i work at a Dutch trailer manufacurer.
In cooperation with an importer and a factory we are developing a new axle based on a standard torsion suspended axle.

this new axle uses the same brakes but without the crappy bowden cables, which are a PITA because they stretch out or seize up over time. The new system uses solid pull rods and levers instead.

Because of the brake construction we cant use individual suspension anymore, and we're getting a rigid axle.
Many customers want a car hauler for 2 or 3 cars, with air suspension so they can drop the trailer rear end to lower the approach angle of the drive ramps, for low clearance sports cars.

If we want to offer customers another suspension option, what would be a cost effective substitute for air suspension ?
Rubber suspension isnt possible because of the rigid axle body.
So we could mount coils or leafs to the axle...

How does the ride of parabolic leaf springs compare to the ride of air, or rubber suspension ?
I suppose multileaf suspenson saves the cost of shock absorbers too ??

please tell me how you find your leaf springs on utility trailers and car haulers.

 

[Z-Michigan]

If the design is already setup for air springs, I would think coil springs would be a drop-in fit.

Here, a trailer would more likely use leaf springs because they are cheap and spread the load across two distant points, reducing point loading. Leaf springs do still require some kind of shock absorber (damper); in the old days a leaf without a damper was better than a coil without a damper, but I don't think it would be acceptable today. Undamped springs that I see are generally rubber donut types.

We all have pickups here in the US and all pickups have leaf springs. They work perfectly fine. I don't notice much difference in ride quality for a similar sized vehicle and spring rate (i.e. load capacity). Cars had leaf springs here up through the 1970's.

 

[Renze]

Z-Michigan, the general idea is to offer a low cost alternative to our premium Firestone AiRide based suspension.... There is no substitute for an air ride, so the price would be the only reason to go to mechanical suspension.

That firestone belly isnt the major cost, the shock absorber and carrying leaf are just as expensive.
If we could do without the shock absorber, that would be a cost benefit

 

[Bird]

all pickups have leaf springs

I think you're right, but my first brand new pickup truck was a 1969 half ton, short bed Chevy; cheapest thing available at the time, and it had coil springs under the rear end. That same year, an uncle also bought a new 1969 Chevy, but it had the long bed and leaf springs.

If we could do without the shock absorber, that would be a cost benefit

I never had shock absorbers on utilty or boat trailers, but they were basically smaller trailers for lighter loads. I learned many many years ago to never buy a travel trailer (RV) without shock absorbers.

 

[Z-Michigan]

If you're producing large quantities, leaf springs and a damper can be done quite cheaply, based on costs I see to buy replacement parts here.

Even cheaper yet might be the rubber donut torsion system that is on our horse trailer. But I don't ride back there and I'm not sure how the horse likes it. It seems to me stupid to put such a crude system on a horse trailer, but that's how it is (ours is top of the line too).

John, I'm referring to modern conventional pickups. I can think of the Honda Ridgeline and Chevy Avalanche as vehicles that look sort of like pickups and yet have coil springs; however, both are SUV-based and not really intended for hard truck type use.

 

[wushaw]

Most of the utility, flatbed, box and whatever else except "RV/Caravan" type trailers don't use shocks.
Leaf springs are the cheapest.
Tandem axle leaf is the most common. The ride is not too bad, I have never had any complaints out of my tractor

 

[Renze]

Even cheaper yet might be the rubber donut torsion system that is on our horse trailer.

I'm not sure what you mean with these rubber donuts ?

 

[Z-Michigan]

Take a look at this website:
GKN Rubber Torsion Axles

I don't know whether this is the same brand as what's on our horse trailer, but I think it's basically the same design at least. After looking at it it may cost more than simple leaf springs, I don't know.

 

[MrJimi]

And here is another axle some of you may be familiar with, I have these under 2 trailers I own and I love them
Dexter Axle - Trailer Axles and Running Gear Components - HOME

 

[Renze]

O.K. in Holland we just call that a torsion axle...
With the new pullrod brake system with central air booster, we cant use individual suspension anymore.... It has to work on a rigid axle