Scrambler B

[iYOA]

what does a compressed spring braking system look like
could someone plz explain or send a link to an image?
thanks.

[croman74]

Here's a animated video of how it works off of the wiki http://scioly.org/wiki/Image:SC-brake3.gif

[LolBubbles]

sp the metal thing/ wood block pulls the nut to a stop or yanks it?

[bob3443]

the nut pulls the "pin" out of the wooden block, which lets the wooden block fall down and hit the floor, lifting/stopping the car.

[cryjea]

I'm using the wingnut braking system. That is working pretty well.

[scichic34]

we're just using a string, but it's not working, so i think we'll switch to wingnut

[croman74]

Wing nut works really well and is really easy to build. I don't think that it is necessary to build a brake pad.

[zbuilder]

Wing nut works really well and is really easy to build. I don't think that it is necessary to build a brake pad.

The problem with the wing nut it that it completely stops the wheels so the car skids. Since you don't know exactly what surface you will be competing on it is very difficult to get really accurate stopping with that system, unless the scrambler is very slow. You need a system that gradually slows the car at a predictable rate, without skidding. Even the braking block system will be unreliable at very high speeds, unless it has some way other then skidding, of gradually slowing the vehicle. You can't stop anything instantly, there always has to be some period of decceleration.

[bob3443]

someone previously mentioned put a piece of a sponge to where the wingnut goes to, this will slow it down before it completely stops, the larger the sponge, the earlier it starts to slow down.

[fleet130]

An improvement I've seen on the threaded axle/wing-nut brake is the compression spring modification. Instead of the wing-nut contacting a hard surface such as the vehicle frame or another nut locked on the axle, a spring is placed between the wing-nut and braking surface. This ads friction as the wingnut compresses the spring and slows the vehicle down before the brakes lock.

Another brake I've seen used with good results is the "band" brake.

This brake can be modulated/feathered to produce gradual deceleration. If you get the direction of rotation backwards, the brake will lock up when applied and skid the wheels.

The most common drum Ive seen is an empty thread spool; however, bare wood is rough and tends to "grab". I've seen vehicles where the "drum" was just a smooth spot on the axle.

A weaker spring in the actuating linkage permits more gradual application of the brakes. Rubber-bands work well and it's easy to switch to a smaller/larger size to adjust how hard the brakes are applied.

The "band" may be nothing more than a piece of string. It may work better if it is wrapped completely around the drum (approx 1-1/2 turns) before it is terminated to the chassis. More turns can be used on smaller diameter drums.

In my observations, these brakes are a little difficult to set up and adjust, but once they're adjusted, they work well and are reliable.