Idler Roll Replacement

As the thread on ‘Belt Tracking’ has now changed to a discussion on ‘idler roll replacement’ I thought I would start a new thread on this topic. Idler roll replacement can be a difficult task with a high risk of back injury occurring and mining companies are looking for lighter rollers, that use hollow shafts and plastic or aluminium shells to reduce the mass of the roller and to reduce the risk of back injury. Several companies are also developing some fancy idler designs to make this operation easier and safer.

To solve the problem of removing idler rollers under the skirt plates one can use retractable idlers that are available from Sandvik’s Prok idler division in Perth or dropdown idlers from Prok or from H and B Mining Products www.handbmining.com.au
To remove idlers from normal trough frames H and B have a tilting idler and a Mr Corey Matters, also based in Perth, has a slide out design try corey.matters@bigpond.com . Cove Engineering in Sydney also have an idler changing system www.coveng.com

On the 20 km Channar overland conveyor, which is fitted with bent pipe frame idlers, the idler roller replacement operation is carried out from ground level. The belt on this fully covered conveyor is raised up by using a ‘Bull bag’, a heavy duty rubber bag normally used to raise a 4x4 vehicle using the vehicles exhaust gas, this bag is placed on the return belt and inflated thus raising the carry side of the belt. A ball valve is used to lock in the exhaust gas. The idler frame design is such that a pinch bar or screwdriver can conveniently be used as a lever to loosen the roller in its slot, after which the fitter lies on the return belt and removes the roller using both hands in an overhead position. The bull bag is also used to raise the return belt when return rollers need replacement. Planning the idler roll replacement at the design stage of the conveyor allowed this simple and safe method to be developed and implemented without the need for fancy idler frames.

I will be interested to see what other ideas people have on this topic.

Regards,

Dave Beckley
Principal
Conveyor Design Consultants of WA
Perth, Western Australia.

Further to the above information; in the website www.mining-technologies.com under Products ansd Services you will find info on the Cove Engineering idler replacement system and in the same section under 'Surpus Conveyors' there are some detaills of the Corey Matters retractable system that can be accessed from one walkway.

Regards,

Dave Beckley.

Hi David..
We have recently commissioned our part of the Sishen Iron Ore Expansion Project here in RSA, and have some built pretty heavy wide belts.
We are now about to design the belt lifting device to lift the belt off the idlers to change them.
The device will be quite light and adjustable up to 2.4m wide.
The concept is to put the device on the stringers over the belt, thread though a nylon strap under the belt, and hoist the belt up using a hand winch.
I got the idea when I was winching my boat onto its trailer using its hand winch and strap.
Regards
LSL Tekpro

Graham,

Thanks for your input to this topic ; having lifted the belt with the sling you will still have the difficult job of lifting out the heavy rollers. What does each roller weigh?

I have seen a similar device used on coal conveyors in the Eastern side of Australia. The belt lifting unit is placed on top of conventional stringers and a long lever arm is rotated on the outside of the stringer, this lever is attached via a shaft to a central lever fitted with a roller and this rotating inner lever raises the belt. The whole thing is made from aluminium to keep the mass as low as possible.

Regards,

Dave Beckley.

Hi David..
The requirement from the iron ore mine was actually limited to lifting the belt only, as they consider this to be far more onerous than lifting the rolls.
In a convex curve on the wide heavy duty belts, the lifting force required is very significant. A moby-lift is good for this if you can get it near the belt.
I am no Chuck Norris (more of a Russel Crow really), but even so, I have never really had a problem changing out rolls, with a little help from my trusty Zulu friend and a obviously a Crow bar.

Cheers
LSL Tekpro

Graham,

That is interesting but you did not mention the roll mass. In Australia the OH&S people are pushing for lighter rollers to minimise the number of back strains. One coal port in NSW used three roll idlers with each roller having a mass of 38 kg, for their upgrade they stipulated a maximum roll mass of 20 kg! This mass was achieved by one supplier by using a hollow steel shaft and an aluminium shell. Other suppliers went for 5 roll idler sets to reduce the roll mass. The race is definitely on in this country to develop lighter rolls and better ways of replacing them.

Regards,

Dave Beckley.

I did not know of your Australian roll mass limitations David..

Here in South Africa, OH&S has not caught on to this issue.
Give it time I suppose.

Cheers
LSL Tekpro

An interesting topic. How much load would you expect the lifter to carry for a big belt?

Graham,

If you have a look at horizon-conveyors.co.uk they have an interesting looking belt lifter, that I assume is similar to yours.

Regards,

Dave Beckley.

Thanks for that David..
The belt lifter with the hand winch (a la boat trailer) is pretty much exactly what I have in mind.
Cheers
LSL Tekpro