Spring Tensioned Return Rollers

[Allan Richards]

All,











I've just started using photobucket and up loaded these photos to use i the forum. I think I need to re-size them so any tips on how to do that.

This is the spring tensioner that I've been working on to protect from broken track links. As you see with the screw driver it works as this would have been a guarrentteed broken track without the spring. Its success is the amount of spring tension, too little and the tracks go slack all the time, too much and its no advantage over no spring.

[Allan Richards]

All,

I don't know what happened to the words on the mud scraper but this is a little device I made to protect the rear return roller from picking up stnes trapped between the track horns. It works and is not too visisble when the track is on and the tank on the ground but the little shovel needs to be spring loaded as it easily gets bent up when rigid as this one is.

[Joe Boylan]

Hi Allen - I am interested in how you came up with the right spring tension? Is there a spring # or size. I am getting ready to install my wheels and have been thing along the same lines - some type of spring loaded assembly to keep the tracks tensioner movable and keep them from breaking the tracks when rocks get in between. Looks as if you have found a simple and effective one.
Joe

[Allan Richards]

Joe,

The right spring tension is purely by trial and error. The springs are from an old folding garden chair and just looked about right. I've made one end adjustable for tension and you can vary the point at which the cable attaches to the track adjusting arm. There is quite a bit of mechanical advantage between the track adjusting arm and the return roller as the offset of the return roller axle from the main axle which goes through the side of the hull is quite small. Basically you need the tension to be enough not to move when you do neutral turns on grass (which puts a lot of strain on the tracks) and yet will move when something gets stuck in the tracks.

[Patrick O'Donnell]

Allan,

I am looking at your snaps with much interest. I used to have a spring track tension system on my metal 1/10 scale metal Jagdpanther, but when I tried to do neutral turns on wet English lawn grass the tension system came into operation and closed-up resulting in a thrown track. There was no problem with neutral turns on a flat surface, but the grass was a real problem. The tension system was original, consisting of two springs to each track with adjustment to vary the spring settings. I hope you are successful with your experiments and please keep us informed with your excellent snaps.

[Allan Richards]

Patrick,

There has been quite alot of work done on the 1/16th tanks with spring tensioners and they have exactly the same problem with getting the tension set right and have used combinations of R/C car springs and shock absorbers to tension the track. I think the secret lies in making the spring pull hard against a stop to keep the track tensioned just as with the screw system designed by Armortek, but the advantage of the spring is that it will give if something untoward happens like a stone, or in the test case, a screw driver gets in the works!! A lot of people think that the spring is pulling to keep the track tensioned but in my design the spring is too strong for that and is designed to keep the track tensioner against its stop. I don't think you can design a system to have the spring tension the track and at the same time hold for neutral turns because nuetral turns on British wet grass put a great deal of strain on the tracks which will always overcome the spring tension required to just hold the track at the correct tension for normal running.

Sounds complicated but I hope you see what I mean.