Dear Horatio,

There is another way. Letting the idler frame drop to remove the roll from the frame without having to lift the belt.

If you lift the belt, you must overcome a blet sag length which may span many idler spacings and also require a very strong force.

If you drop the belt between the idlers you do not need to displace the belt to the same level and therefore it takes significantly less force.

We developed a impact idler cam system, for the Palabora tunnel belt in their copper mine in RSA, that did do this job. It was then later improved to use on conventional idler frames again in RSA. This also implies that the cam system must be installed for all idler frames at one per side. This is an additional expense, but which has a payback in not having to transport the machinery to each idler. If a roll is failing, the roll can be immediately removed from service without shuting down the belt. The roll is then later removed on a scheduled down pweriod.

Henderson mine has written about their idler changeout mounted on the remaining tunnel train track system. This is a system which has the least manpower effort and probably quickest replacement time cycle.

Write to my email for further interaction.

There are other optional practices and concepts that have been in reviewed for tunnel systems. Are you looking for a quotation or partnership? ■

Hi,

As Larry advised the drop down idler frame is used extensivly in S Africa.

We use it for both impact areas and conventional run of structure.

Regards

Phil Staples ■