The first such installation was applied to the 96 km phosphate mine in the Sarah desert in Morocco. The installation is called Phosbucraa. It was installed by Krupp in 1972. The trolley ran on the stringer steel with a conventional belt with elevated sections to allow passage on the sand dunes. Krupp still have promotional literature on the assembly. The trolley had a robotic pendant that changed out the idlers.

Interesting that both Krupp and then Hewitt Robins proposed similar maintenance cart ideas for this project. Now they are one.

THere are, according my memory, eleven flights with most ranging in length between 8 and 11 km. A trolley was dedicated to each flight.

Phosbucraa had many accidents which killed workers, with the trolleys falling off the structure. The wheels had no holddown assemblies. THe belts dynamic response caused material to be thrown upward which dislodged the flat corrogated roofing over the belt and deposited material on the structure. I suspect this contributed to the safety issue.

All trolleys have been removed for safety reasons.

Skyline Mine, in Utah, USA has installed the maintenance trolley on an elevated pipe conveyor. This is a concept I forwarded to the client during the feasibility phase where access is remote on a mountain side. Krupp-Robins installed this as well. However, they did not account for the icy conditions. The trolley went out of control on the downhill slope. Eventually, the trolley design was made to work. I believe it is still in operation today.

Richards Bay, South Africa has such a trolley on a elevated pipe conveyors. This too was a concept I proposed with my ex-associate Mr. Phil Staples of CKIT. They now have multiples of this maintenance trolley at Richards Bay. I believe he is now promoting this in India for FFE.

We are installing one on an elevated 7 km overland conveyor in Nigeria for Dangote Cement using a conventional belt. THis is in partnership with ETS South Africa. THe system will be commissioned in May 2005.

Aumund is installing one for Lafarge Cement between India and Bangladesh. on a 17 km conventional overland troughed belt.

We worked on a 143 km elevated overland feasibility to route a conveyor over farm lands and coal fields for ESKOM. This is still under study.

There are many interesting design criterai that must be considered to make this concept perfrom well and be economical. ■

dear nordell, thanks for your valuable information.

regards, anil seth ■

There are presently 5 maintenance trolley systems in operation in Southern Africa, and we are developing another two in India.

The plan is to eventually make them a fully mobile and automatic maintenance tool able to check and replace idlers as it travels along the conveyor.

Working with Prof G. Lodewijks we hope to at lest have the monitoring process in operation by the end of 2005.

Thanks

Phil Staples

Ckit ■

Dear Mr. Phil,

How this trolley maintenance system is effective?What are the problem in this system?

In birla copper, Dahez,Bombay pipe conveyor with steel cord belt having 90 deg . bend. Is 90 deg bend is recomendaed for steel cord belt?

Please give some information on the same also.

Regards.

A.Banerjee ■

According to the hazards described in the previous thread it seems that there were vehicles operating without due regard to basic passenger safety considerations. It seems prudent to ask what, if any, statutory regulations have, or should now be, applied in the trolley operations.

While the economics of the service car might be admirable it could be seriously compromised by a mandatory shut down, accident investigation & obvious subsequent litigation in the event of an incident. If you run a conveyor through populated areas then there should be provision for fire fighting access etc. trolley or no trolley. Stringers will have to be strengthened to carry the weight of a safe carriage loaded with personnel, driveline, engine, fuel, air-conditioned cabin, maintenance machinery & conveyor spares.

At the end of the day I imagine it is the operational benefit of a safe trolley rather than the initial installed cost saving that makes it so attractive. ■