If you are using a cable supported conventional idler supprted belt there are a lot of belt brakes available.

It might simply be that the coveyor is overloaded and that is why the brakes are failing.

Does your head pulley have an extended shaft that also supports the belt brake? ■

Run-back has conditions that contribute to instability:

1. rate of deceleration with or without braking

2. jerk effect either starting or stopping

3. shape and size distribution of ore

4. filling of crossection

5. surface roughness or lack of

6. belt modulus

7. drive inertia

8. slope angle

9. type of take-up system

10. enough!!

Harse stopping will cause a momentary transient elastic wave response with a diffferential velocity and displacement. This induces a vibration with various properties that will yo-yo the internal shockwave response over time till is goes to a steady-state which may be at end of stopping cycle.

Taking the above, when the belt is stopping, there will be a point when the head/drive pulley stops forward motion. Depending on the rate of deceleration, a greater or lesser reverse response of the loaded carry strand will occur as the belt re-establishes a gravity force which causes the belt to reverse direction. The reverse direction is similar to a spring in rebound which has a sinusodial continuation till it damps to a stop. This yo-yo effect can unstabilize the ore on the belt, according to items 1-7, which may cause the material to become unstable and roll-back.

Higher slopes will have a greater yo-yo effect as will lower drive inertia.

We see this phenomenon often on high lift belts designed years ago. Today we tune this effect out so spillage and stuffing of the loading station do not occur.

Hope this is helpfull. ■

Sorry the I did not include a comment on the anti-roll back device.

First, the gear reducer will not have a big effect on the yo-yo.

Yes, there are anti-runback devices, oddly called holdbacks or one-way clutches. They may be an improvement over a brake. Their greatest advantages are that the belt will start from zero forward or reverse motion when the brake is released, assuming you still need a brake.

Note: the belt reaction from tripping a drive will activate the yo-yo. Think of you (the motor) turning the belt with a big wrench pulling the belt up the hill, let's say at near zero speed. Now, let go of the wrench. All the tractive force will try to equalize between tight side and slack side of drive. This is what is happening at full speed when the motor power is cut. The differential tension tries to equalize, overshoots its equalibrium back and forth till equilibrium is reached. Then it happens again when the belt comes to a stop at the head pulley. It may also do this mulitple times when braking with an erratic control. ■