Time Has Passed Me By.
Why should the trolley be free to move when the belt is starting? Put the brakes on when the relvant bunker top is reached. You're talking about a part of the world where any and every short cut is applied. In the safe real world there is a 3 minute warning delay before any conveyor is started. There should be ample time to reposition the tripper. A vehicle has been set to move under the influence of belt tension and tractive effort. Without brakes it is sure to move whether the belt is starting or stopping. This is the first time I heard of a tripper moving out of control and clouting the buffers which proves you're never too old to learn. Get the operations manager to do the cleaning and see what solution he comes up with. ■
John Gateley johngateley@hotmail.com www.the-credible-bulk.com
Re: Tripper Movement Due To Belt Pull
As suggested by others, I would have guessed the tripper should be "locked" while starting the conveyor.
Perhaps what is there has stopped working effectively; or this issues was not originally recognised, and now maybe an "upgrade" is required.
I am aware of similar issues during commissioning where when pressed for time the tripper LT is "left for latter", and then personnel that are not aware of the physics are surprised when the conveyor is started.
Regards,
Lyle ■
Trouble With Trippers
My first and last question is:
Why is a reduction geared double drum winch not employed to move the tripper trolley along the X axis?
That is the way it is done as a rule.
Hopefully we will have an answer sometime. ■
Possible Reasons
Hello,
there might be imo two basic reasons for the effect, with one remedy (brake/s) as already proposed above.
First would be the effect from geometrics, pls. refer att. sketch, assuming the belt tension T does not alter (significantly) when passing the two pulleys.
DOL start of belt could produce a belt force peak which then could overcome breakaway forces in the trippers drive system (wheels, gears etc.) and then also e.g. downhill slope part of gravity may play its role.
Second could be an reactive impact force onto the baffle plate / chute at tripper discharge.
Regards
R. ■
Tripper movement due to belt pull
In traveling trippers (mobile trippers) used for bypass feeding in bunker bay, a frequent problem encountered is the movement of tripper due to the belt pull. It is reported at many sites that the tripper moves because of the belt pull (not by the tractive force created by the travel drive motor) especially when the conveyor is accelerating. That is, suppose the tripper is moving in forward direction (in the direction of belt movement). When the conveyor accelerates, the tripper has a tendency to move in a faster speed (normal desired speed is 0.1V, where V is the belt speed; There are cases in which tripper has a tendency to move even at belt speed). Due to this tendency, the moving belt imparts an additional force on to the tripper additional to tractive force generated by travel drive motor. This results in sudden and faster movement of tripper which even causes it to hit the buffer stopper. One preventive method which I feel is to use a scoop type fluid coupling for the tripper conveyor so as to ensure slow and smooth start which will reduce the starting tension on the belt. But most of the cases, the tripper conveyors are driven by LT motors for which customers specify/ vendors use traction type fluid coupling for which the acceleration coefficient is 1.5. What is the design aspect to be taken into consideration for avoiding this? ■