Speeding up Wagon Unloading

Conveying & Transportation

Speeding up Wagon Unloading

C-Frame type Tandem Rotary Tippler and Transfer Platform for high capacity Wagon Unloading in India
Railway transport is one of the most important means of transport for huge amounts of dry bulk solids. Often, train unloading is a bottle neck of such systems. A solution to this problem is presented in this article.
(ed. WoMaMarcel - 13/2/2015)
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The tippler is controlled by PLC system in either manual or fully automatic mode. The drives for tippler are either variable speed controlled electro-mechanical drives or hydraulic drives.

In case of a hydraulic drive, the hydraulic power pack can be kept away from  the dusty environment in a separate closed pressurized room. Electric panels of VVFD drives are protected from dusty environment by placing them in a separate airconditioned room.

Variable speed controlled electric drives are advanced and effectively used with regenerative braking for both tippler and side arm charger - with consequent reduced demand on the power network. This regenerative feature is not available with hydraulic drives.

In a mobile machine like side arm charger, indexer and puller cum pusher of transfer platform, it is recommended to provide electro-mechanical drives with VVVF control. We can place the VVVF panel in a separate closed pressurized dustfree room inside the control tower, and the power is supplied to the drive motors through flexible cables using an energy drag chain or a festooning arrangement. Such an arrangement is not possible with hydraulic drives.

In case hydraulic drives are applied for side arm pusher, indexer or puller cum pusher for tandem tipplers, the size of the power pack will be much bigger and it becomes difficult to accommodate the power pack on the machine platform. This increases size and weight of the moving machine and makes it unstable. Furthermore, during frequent starts and stops and forward and return movements of the machine, the power pack experiences jerks, and is additionally exposed to environmental hazards like dust, heat and rain – which is not desirable.

A typical installation of a tandem tippler consists of tippler, wagon positioner, side arm charger, wheel grippers, hopper and apron feeders:

  1. A positioner (or indexer) which pulls the loaded rake over a distance of two wagon lengths towards the tippler platform on the inhaul side. The two wagons are decoupled and pulled further towards the tippler platform.
  2. Wheel grippers installed on the inhaul side engages with the front wheels of the first loaded wagon standing on the inhaul side, ensuring the fixed position of the leading wagon of the loaded rake. Wheel grippers are hydraulically actuated and horizontally arranged. Another set of wheel grippers installed just before the platform on the inhaul side ensures that two wagons are maintained in fixed position, when indexer arm decouples and the side arm charger (SAC) arm couples with the two loaded wagons.
  3. An SAC which pulls the two wagons on the tippler platform. Simultaneously, the SAC pushes the empty wagons standing on the platform (from the previous unloading cycle) to the outhaul side.
  4. Another set of wheel grippers installed on the outhaul side engages with the rear wheels of the last (tailing) empty wagon standing on the outhaul side, ensuring the fixed position of this last wagon of empty rake.
  5. The SAC continues pushing the empty wagons out of platform with controlled speed until they couple with the last empty wagon of empty rake standing on outhaul side. The wheel gripper is now disengaged so that SAC can continue pushing the empty rake through a distance of two wagons and thus continue to form the empty rake on a level track (or max stipulated gradient of 1:1200 as per RDSO guidelines). The last wagon is then gripped and SAC decouples its arm and returns to original position to take charge of the next two loaded wagons placed by the positioner – and the cycle starts again.

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