Travelling Gantry Crane from a 1913 Meccano Manual

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A Travelling Gantry Crane from a 1913 Meccano Manual. Various slightly different versions were published between 1909 and 1914. Frank Hornby may have seen the full size version on the Liverpool dockside. I suspect that he was intrigued by the mechanism which kept the load at a constant height when the trolley carrying the hook was traversed across the gantry. However, in the published model this would not work. This has been corrected in this version.
The model was first published when wheels were secured on their axles by "tunnel keys". The version that I used was published just after Set Screws were introduced. Only the parts list and the design of the Single Bent Strip had been altered. My model uses Wheels with Bosses and numerous Collars instead of Clips (Part no.35). One "tunnel key" part (a no. 24) remains as a weight for the hook as well as some of the 1" pulleys . Contemporary parts have been used including original bolts - about 3/32" longer than later ones. Careful planning was needed to prevent them interfering with each other at corners. Builders using shorter bolts take pride in ensuring that only bolt heads appear on the outside.
The mechanism for causing the load to remain at constant height while the trolley is moved along the gantry works as follows.

The hoisting and traversing winding drums can be connected together by a chain of 3 gears (shown on the still photograph in the video). To hoist the load, the gears are disengaged by means of the lever sticking out of the side. The handle on the the right can then be turned to raise the load. To lower it the black pawl has to be disengaged.

To traverse the trolley, the 3 gears are put into mesh using the lever. The left hand handle can then be turned to move the trolley. As the trolley moves the load is raised or lowered at the same time so that the load remains horizonal. 3 hands may be needed.

The third handle can be used to move the whole gantry.

The model was brought to my attention by another member of the North West Meccano Guild - Brian Eldridge, who in turn found out about from another Meccano enthusiast Allen Esplen.
Brian has used the simpler method of taking the free end of the hoist cord to the far end of the gantry - method used on builders’ Hammerhead Tower Cranes to keep the load at constant height during racking.
I think that the reason for the complicated and expensive mechanism is that the original crane was fitted with snatch blocks. The hoist rope could be unhitched from the blocks so that light loads could be raised quickly. For heavier loads, the rope could be hooked back round the pulleys on the snatch blocks to give a triple purchase.
The mechanism is sometimes used on the auxiliary hoists of hammerhead cranes, when a single part hoist is all that is needed and avoids the problem of the ropes twisting round each other.