Volume Six - Pre-Victorian to the Present Day - Select Aspects - Reconstruction of Three Tips - 1912 - 17 . . .

The lifting and lowering of the cradle and truck are to be accomplished by means of three inverted cylinders and rams with a balance weight. Two of the rams are to be 10 inches diameter, with 19 feet 6 inches stroke, and one 6¼ inches diameter, with 19 feet 6 inches stroke, all placed on one side of the tip, with the 6¼ inch diameter cylinder as the centre one, and all working in the ratio of 2 to 1. The working range of the tip is to be 38 feet, and the total height of lift to be 41 feet above the level of the coping of the Dock wall, the additional 6 inches of stroke of the rams being given to allow for the taking up of any slackness there may be in the main lifting ropes.

The two outside rams of 10 inches diameter are to operate together for lifting wagons up to the gross weight of 20 tons, and the third, or centre ram, will be brought into operation to admit of wagons up to 23 tons gross being raised or lowered.

The balance weight is to be connected to the crosshead of these rams, and is to work in guides of sufficient length and ample proportions. The collective weight of the hydraulic rams, crosshead sheaves, and balance weight, etc., is to be so arranged that the weight of the cradle and an empty truck of 4 tons weight will have a margin of 20 per cent. over that of the rams, crosshead sheaves, and balance weight, etc.

Ample provision must be made in the fixing of the main lifting and tipping cylinders to the main structure, for taking the full load of all cylinders when at full pressure of 750 lbs. per square inch.

The tipping of the trucks is to be done by a multiplying ram, 12 inches diameter, working at 2 to 1, in a cylinder fixed to the main structure of the tip, above the lifting cylinders.

The return low pressure water is to be discharged from the cylinders, in the first place into a tank placed high in the framing of the tip, so as to give free release to the water before being conveyed back to the pumping engines by the return mains.

The cradle is to be thoroughly well constructed and fitted with sliding stop bars to prevent wagons running backwards off the cradle ; these stop bars to be operated by a lever in a convenient position.

The cradle is to be not less than 26 feet long and 14 feet 6 inches wide.