Springless Tandem Trailer (Toggle)?

[andyfletcher]

I've see many of these trailers around. They don't have springs. The running gear comprises a center unit similar to what the equalizer springs are attached to. If you can imagine an inverted "T", the leg is bolted solid to the frame so it can't move. There is a bolt that passes through the cross beam through the leg. At each end of the cross beam the axles are attached. Sort of like bogey wheels you see under tank tracks.

The front axle rolls over an obstacle and the beam is forced upward, carrying some of the load to the rear axle because that end of the beam is forced down. Same happens to the rear axle except in reverse.

I was trying to find something bad about the design, but it
does provide for shock in a sense by distributing the force.
Overall the ride would be rough and hard on the bearings I suppose. I imagine the axle would have to be through bolted to the beam as "U" bolts will eventually come loose in this type of setup.

Anyone else see these.? Just saw one go by this afternoon
carrying a bobcat.

 

[Bird]

Andy, you're talking about a "walking beam" suspension which is not uncommon on big trucks, although I think they're usually in combination with springs or air ride such as this.

 

[TOMDUALLY]

I have seen these on "Rollback" trailers and they have airbag suspension as Bird described. The interesting thing about this is the suspension, it is mounted to a carriage that slides back and forth under the frame of the trailer with the use of a winch. Pull the axle assemble forward and the rear of the trailer deck drops to the ground for loading then reverse the winch pull the axle assemble back lifting the trailer back up to orignal position lock the assemble in place and your on way , to unload repeat. NO RAMPS NEEDED /forums/images/graemlins/laugh.gif /forums/images/graemlins/laugh.gif /forums/images/graemlins/laugh.gif

 

[rambler]

My brother in law just bought a dual tandem something like 20,000# trailer with a walking beam like that, no suspension. It's a bit of a work in progress, no floor at the moment. It rolled home 50 miles pretty nice empty.

--->Paul