The need for a maintenance walkway has in the past made elevated conveying especially an overland conveyor cost prohibitive. However the introduction of the elevated triangular gantry with a maintenance trolley in place of the walkway now addresses many of the issues previously used to promote trucking in place of conveying.

When one considers, land sterilization, (by cutting off farm land access), security fencing to eliminate theft and prevent injury to both human and animal, the risk of bush fire, and the need for road access, then the elevated conveyor structure is more acceptable.
 
This structure takes it lead from the extensive developments of large span architecturally pleasing structures such as roof structures. Using the high strength of pipe structure this is approaching the optimum design of low cost high span and lift solutions.
 
Like its own development however, it requires a re-look at the way conveyors have been built in the past and specifically the support structures for the idlers and the way the mechanical components are maintained on the conveyor structure.
 
However, it does open the door to its use for all types of conveyor including in some instances to the use for long distance overland conveying.

Obviously a major requirement of all conveyors is the need to access the total conveyor for inspections to the mechanical equipment and in the event of failure to be able to carry out basic maintenance; this function is usually carried out from a road running along the length of the conveyor.

The quality of the road depends on the terrain and environmental consideration; basically the susceptibility to wash away and erosion is critical to the actual quality of specification to the road construction.
 
Enters the Maintenance Trolley. It is a self propelled trolley that fits onto the triangular gantry, which allows for basic scheduled maintenance of the conveyor system.
 
The trolley is independently powered usually by its own onboard diesel engine drive and allows quick access without fatigue.
 
Substantial savings in structural costs result in adopting the triangular gantry design with the added efficiency of maintenance personnel.

The quick release idler has been developed to incorporate a conventional tubular idler frame, mounted on a special bracket that can easily lower the idler away from the belt for maintenance.

This feature i.e. the ability to lower the idlers away from the operating belt, lends itself primarily to use in haulage shafts and other conveyor applications where the belt tensions are so high that idler change outs are very difficult without special rigging equipment.

It is also convenient to the Beltsman who is able to travel the conveyor release damaged idlers, which otherwise would in turn damage the belt, enabling there idlers to be replaced and re-engaged during the convenience of a shut down.
 
 
One can see the conventional tubular idler support frame, however the end connection to the frame has been changed to incorporate a sliding bracket, which can be lowered by the Beltsman to remove the idler and frame away from the belt.
 
The idler is lowered far enough away from the belt to allow it to be lifted out of its cradle are replaced without having to lift the belt.

With a view to making the belt conveyor more competitive both in capital and operating costs an exercise to re-engineer the conveyor structure was undertaken to make it more friendly to the conveyor belt and more cost effective to install and maintain.

The basic principle of these structured revolved around using the line stands (legs) as the carrying structure for the idlers and using a very light section to support the wind sheeting.

With a view to making the belt conveyor more competitive both in capital and operating costs an exercise to re-engineer the conveyor structure was undertaken to make it more friendly to the conveyor belt and more cost effective to install and maintain.

The basic principle of these structured revolved around using the line stands (legs) as the carrying structure for the idlers and using a very light section to support the wind sheeting.

The aim was to develop a structure that was both belt and maintenance friendly, using the minimum amount of line stands thereby reducing civil costs and being practical for both overland and plant conveying systems.

An underground decline conveying system was to be developed which lent itself perfectly to this development. The conveyor was required to operate in a confined space (tunnel), it was necessary to minimize the civil scope because of the difficulties in accurately constructing foundations and the belt had to be protected from operational damage at all costs.

The designers opted for a pipe construction for the line stands and the wine glass format was born. Being mounted on a single central support the frame was easy to build and required half the foundations of conventional systems. Alignment was also simplified by allowing the frame to be leveled in a three dimensional plain using the 4 centrally positioned holding down bolts.

In the event of damaged or lost idlers belt simply runs on the tubular frame, thus unaffected by sharp steel edges.

To overcome the problem of line stand spacing in curves the carry idlers were moved off the line stand and placed on a support stringer spanning between the line stands.

The return idlers remained on the line stands thus the distance between the line stands became a function of return idler spacing only, which in most instances can be 10m or more.

The design of the support stringer now becomes the area of structural optimization with numerous sizes and shapes of stringer and stringer connection being considered.

The optimum shape was shown to be the cold rolled Z section which has the advantage of being made to any basic dimensional requirement and thus could be dynamically tuned to suit the structural loads and conveyor dynamics. Allowing the carry idlers to be placed on the stringer has two distinct advantages firstly, the idler support frame could also be tubular (again belt friendly), and the recently developed quick release idler frame could also be used in the required areas.