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Incline Railway Control Circuit

Incline Railway Control Circuit

The mechanism is driven by a geared slow speed motor and controlled by an electronic timer circuit. The car waits for a preset time at the top and bottom of the incline before being slowly lowered down or pulled up the track.
Drive Mechanism Part Descriptions

GROOVED TAKE-UP DRUM – A cast aluminum drum with a continuous smooth groove, much like a thread. The drum winds in or pays out the cable (cord) as it rotates. One end of cable is fixed to the drum and enough is wound onto the drum to allow for the total length of travel of the car along the incline. As the cable is pulled in or payed out the car is raised and lowered along the track. The diameter of this drum greatly affects the speed of movement of the car. The diameter should be as small as practicable for the length of cable needed for the cars travel. A smooth drum could also be used as long as the cable will lie flat when being drawn in.

The CABLE is a thin cord that will not stretch and is not overly elastic so that the car does not have a jerking motion as it travels. Some experimentation will be needed to find the right material.

TRAVELER BLOCK – A solid brass piece that has smooth holes to follow the guide rods on either side of the mechanism and a threaded centre hole so that as the drive shaft turns the traveler moves back and forth. The small holes in the top of the traveler are for lubrication. The brass rods that extend from the ends of the block make contact with the springs and are used to operate the control circuit.

BRASS TERMINAL BLOCKS – Form the start and stop switches for the the inclines control circuit. These are small blocks of brass with a horizontal threaded hole through the block. A long 6/32 machine screw is threaded through the hole and a wire attached to the block is connected to the control circuit.

6/32 MACHINE SCREWS – Run through the brass terminal blocks are used to make adjustments to the stopping positions of the car. When the adjustments are set the nuts are used to lock the screw in place. The springs on the ends of the machine screws are from retractable ball point pens and simply prevent the rods of the traveler from being bent through repeated contact with the screws.

THREADED DRIVE ROD – supports the take up drum and moves the traveler block back and forth along the guide rods. It was made from round bar stock, turned down and threaded as needed to mount the drum. The drive end is also turned down for the motor coupling connection and to allow a thrust bearing to be formed by the fibre washers and the left angle iron piece. The two nuts set and lock the clearance of the thrust bearing. The full diameter of the rod is threaded with regular U.N.C. thread along enough of its length to allow full travel of the traveler block.

HARDWOOD BOARD – The motor and drive mechanism are mounted on a 1-by hardwood board. The board acts as insulation for the control contacts and the common of the drive frame. A second board supports the drive mechanism and holds the motor.

CAR – The car for the incline railway can be of any design but needs to be heavy enough to travel down the incline under its own weight.

Incline Railway Control Circuit Schematic as Installed

The schematic is for the automatic cable car control circuit that operates the drive mechanism in the above drawing. It is essentially dual timers that are switched by a simple two transistor SET – RESET flip-flop circuit. Two timers allow the time that the car remains at the top and bottom of the incline to be set independently. The outputs of the timers control a solid state double pole double throw relay made with six transistors.

The flip-flop circuit is controlled by two mechanical contacts that are built into the drive mechanism. When the car reaches the top or bottom of the incline one of the contacts is made, the car stops and the appropriate timer begins its cycle. The car waits for a preset time before returning to its previous position. The frame of the drive mechanism acts as the common connection of the control circuit switches.

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