Meccano Giant Block-Setting Crane (Meccano Super Models No 4)
Meccano Giant Block-Setting Crane (Meccano Super Models No 4)
Giant Block-setting Crane (i)
|Arch Two , Area 4|
Meccano Construction Sets (display)
A working Meccano Giant Block-Setting Crane, with separate motors for lifting and rotating, and complex gearing systems, based on the Titan crane manufactured by Stothert and Pitt.
This was the most famous Meccano Ltd. model design ever produced, featuring on the cover of a number of Meccano Ltd. publications, and the plans were available as the booklet Meccano Super Models No. 4.
Block-setting cranes are usually used for building harbours and sea defences. They typically have a huge "grab" that lets them pick up massive blocks of stone or concrete, and from an engineering point of view, these cranes are "extreme" because they require a huge lifting-weight, a significant reach, a great deal of flexibility over where they pick up and place blocks, and a moving tracked base, so that they can continue working at the "edge" of a harbour wall as it grows. The block-setting crane is a special engineering challenge - extreme loads are often handled by a moving gantry crane, with a pair of supports running in tracks on each side of the loading area, spreading the weight and eliminating he need for the crane to be able to "reach". This isn't possible when harbour-building, because the areas to either side of the harbour body (and beyond the end of the built area) are underwater and unstable - the BSC has to be capable of running along the promontory that it is building, with a swing arm that can lift blocks from behind it and place them with high accuracy out in front, where tracks don't (yet) extend.
The characteristic features of the Sothert and Pitt Block-setting Crane were a wide swivel base on four crossbraced tower legs, with wheels driven by giant exposed inner bevel gears, and a gear-room with a curved roof at the counterweight end of the arm.
Frank Hornby's vision for what Meccano was "for" was pretty much focused - one might almost say fixated - on cranes and trains, so it's only fitting that the largest Meccano model design that his company ever produced - the ultimate official Meccano model - was for a crane. The block-setting crane became one of the two main icons of Meccanoland (the other being the Quebec Bridge in Canada), and these two pieces of engineering were regularly pictured on the covers of Meccano publications, and the originals described and redescribed.
Of the two, only the block-setting crane achieved official status, probably because Meccano's emphasis was on mechanisms and a bridge doesn't usually have many (or any) significant moving parts. The original block-setting crane (on the other hand) was the perfect machine to show off what one could build with the Number Ten set (and a few extra parts). It worked beautifully in Meccano, and even the distinctive drive-gear mechanism in the base with its huge bevel gears, when compared to the Meccano version, turned out to be wierdly to scale when photos of the original crane were compared to the Meccano version. It almost looked as if the original crane designers had prototyped the base with Meccano parts, and then simply scaled the mechanisms up!
The crane was also a great way to show off the Meccano roller-bearing plate. A crane this large and this heavy couldn't use conventional axle joint when the beam rotated, as the forces would be so great that friction would tend to carve, bend, and shear through a simple Meccano rod. With a horizontal roller bearing, a machine normally has two parallel plates or rings, one attached to each of the two parts, with the weight of the upper piece supported by a set of ball bearings or radially aligned rollers distributed around the perimeter of the joint, and held in place with smaller axles, or with a ball bearing channel. This allows the weight to be spread over a wide base, with the weight for asymmetrical loads being borne far enough from the central pivot axle for destructive combination of wrenching forces and leverage to be less of a problem.
Stothert and Pitt
George Stothert founded his ironmongery business in 1785, and by the late C19th, the company Stothert and Pitt was increasingly specialising in steam-powered dockyard cranes, with the Titan block-setting crane appearing in (1899?). An offshoot of the company producing steam locomotives, the Avonside Engine Company, operated between 1840 and 1935 under a number of Stothert- and Avonside- name variants.
The basic design was improved and republished with a number of revisions and improvements over the years.
This version was built by Andre Michel, and incorporates these updates, along with a number of additional refinements and improvements engineered by Andre, including an improved drive-gearing design. When we last looked, this seemed to be the most sophisticated build of the crane that we could find.
One of the key improvements is in the crane's main rotational joint. The original crane design used the Geared Roller Bearing, Meccano part 167 assembly, which is now on display alongside the crane (since August 2016). Comparing the "official" assembly with the crane, we can see that part 167 has sixteen rollers mounted around around the edge of an internal "dish" that sits between the two toothed circular plates. In Andre's model, two of these dishes are used, with the rims facing each other, held apart by a set of around thirty-two smaller pulleywheels mounted between the rims.
Since the pulleywheels and dish rims are enough to locate the two parts of the joint, there's no requirement for a central axle, and the centre of the joint is "empty" – although there is a central transmission shaft passing through the centre of the joint, Andre's redesign has no central locator plates and the shaft makes no contact with the surrounding joint itself.
- Stothert and Pitt Block-setting Crane, photograph (commons.wikimedia.org)
- Titan Clydebank (titanclydebank.com) - a grade-a listed tourist attraction, this is a Titan crane configured for general dockyard work rather than block-setting (so it has a fixed base)
- 1914 Titan crane, Bath (bathintime.co.uk)