Trolleys

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The trolleys support the lcad and transport it to the area required by the work cycle. They consist of a variable number of Power and Free trolleys connected by two-bars or load/bars.

There are three types of power and free trolleys:

• Leading
• Intermediate
• Trailing

Leading Trolley

The purpose of the leading trolley is to support the load and/or enable engagement/disengagement of the carrier with the pulling chain by means of two dogs.

It consists of a trolley body (1), 4 ball bearing type wheels (2) mounted on through pins (3) two guide rollers (4) and two dogs leading (7) and trailing (8) hinged on pins. The leading dog (in direction of travel) moves the carrier forward when the pusher of the chain catches it. It is hinged so that when it comes into contact with the stopping blade of a blocking device or the tail of a trailing trolley, it tilts, thus disengaging itself from the pusher.

The trailing or hold back dog, being held by the pusher con­trols the movement of the carrier on the level and especially on downhill sections. This dog is also hinged, giving it the possibility of tilting under the movement of the pusher and to allow its entry between the two dogs. The trolley body is fabricated from two profiled side plates incorporating spacers welded in position to give correct gap between plates. The dogs are cast in pearlitic nodular iron and are mounted on pivot pins made from hardened and drawn manganese steel. The wheels and guide rollers are constructed with integral ball bearings and mounted on steel axles.

 Trailing Trolley  

The trailing trolley apart from supporting and guiding the load stops the carrier and permits accumulation. For this purpose it is fitted with a tail, which on coming into contact with the engaging dog of the following carrier, disengages it from the pusher and allows the carrier to stop. This consists of a trolley body (1), 4 ball bearing type wheels (2) mounted on through pins (3), 2 guide rollers (4) and a tail (7) pinned to the trolley body (6). The external profile of the wheel ensures smooth running along the track without any slipping. The trolley body is fabricated from two profiled side plates incorporating steel spacers. The dogs are fabricated from a hot drawn element. The wheels are constructed with integral ball bearings and mounted on steel axles.

Intermediate Trolley

This is used together with the leading and trailing trolleys when the material to be transported is of uncommon weight or size. In these cases, the intermediate trolley provides extra sup­port and permits even distribution of the weight over a larger number of wheels. If on the other hand, the load is extra long, and a single piece tow bar cannot be used (on horizontal curves and ver­tical uphill sections) the intermediate trolley is used to support and join the centre ends of the two articulated bars. As far as both the body and the wheels are concerned, what has been said with regard to the leading and trailing trolleys also applies here.

Power Trolley

The power trolley supports the chain and consists of two brack­ets bolted together (3), at the lower ends of which a chain support, block (7) is inserted whilst the trolley wheels are mounted on the upper ends (one wheel each bracket) (4). The external contour of the wheels ensures optimal rolling on the runway without slipping. The brackets and chain support block are of machine-finished, hardened and tempered, forged steel. The wheels have been designed adhering to the ball bearing principle and are manufactured in the same material and with .0 the same procedure. The wheel axle is connected to the wheel inner race. The wheels are fitted with a system of' labyrinth protective seals and lubrication is carried out via the grease nipples incorporated in the trolley arms. It is however possible to lubricate periodically using grease guns.