Meccano Giant Block-Setting Crane (Meccano Super Models No 4)

From The Brighton Toy and Model Index
Star Exhibit

Meccano Giant Block-Setting Crane (Meccano Super Models No 4)

Meccano Giant Block-Setting Crane (Meccano Super Models 4).jpg Giant Block-setting Crane (i)

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location:
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.

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.

Block-setting cranes

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 usually better 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 the 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 or from barges alongside and place them with high accuracy out in front, where tracks don't (yet) reach.

The characteristic features of the Sothert and Pitt "Titan" 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.

1904: Titan cranes for harbour-building

... Breakwaters in earlier days consisted usually of rubble mounds-heaps of large rough stones thrown into the sea, and left to the consolidating action of the waves. Sometimes on the summit of the mound was built a masonry wall, faced with hard granite. The construction of such a wall proved, in exposed positions, a matter of great difficulty, as a violent storm would often work havoc with the unfinished or scar end. Engineers therefore endeavoured to imitate nature in substituting for cohesive strength in their structures the inertia of weight of large masses. However tightly bound and cemented small blocks may be, water has a way of burrowing in between them, and splitting them apart. The smaller the block the larger is its surface in proportion to its cubic contents, and as every joint is a vulnerable point in the harness of a breakwater, the reduction of the number of such joints is obviously desirable.

Consequently we find the harbour-builder of today handling immense blocks upwards of 50 tons in weight, and laying them in position by means of very powerful cranes called Titans. Steam, improved machinery, and Portland cement have revolutionised harbour construction. At Gibraltar the Detached Mole is isolated from the nearest point on shore by some half mile of water. The usual rubble mound having been formed as a foundation, a box-shaped steel caisson was constructed in England, shipped to Gibraltar, re-erected, floated out, sunk on the rubble mound, and filled in with concrete, so as to form a mass of about 9000 tons well able to resist the roughest buffets of the sea. The caisson measured 101 feet in length at the bottom, and 74 at the top. It was 33 feet wide, and 48½ feet deep.

Having thus provided themselves with an artificial rock from which to commence block-setting operations, the engineers installed a Titan crane. This monster could handle blocks weighing 36 tons at a radius of 75 feet and less; and yet was not the largest of its kind, for Titans are in use which will pick up a 50-ton block and lay it anywhere within 100 feet of the central pivot.

The Titan is, in general design, a very powerful balanced girder or cantilever, swinging horizontally on the summit of a lofty framework provided with wheels to run on a line of broad gauge. On the one arm are stationed the boiler and winding gear and counterpoises to the weight to be lifted at the other extremity. Beneath the superstructure is a circular roller-path on which it revolves. Gear is provided which communicates motion to the track wheels, and renders the Titan self-moving.

Barges bring the great concrete blocks from the yard, where they are made and kept a long time seasoning, alongside the completed portion of the Mole. The Titan swings round, lets fall its tackle, and soon has the block stacked on the wall behind it ready for use. As soon as the barges are empty the divers descend to the working face of the breakwater to adjust the blocks as the Titan lowers them. The first or lowest course is the longest, that is, it extends farthest horizontally from the Titan, which when dealing with it must take full advantage of its great reach. Each ascending course approaches one step nearer to the steel giant, the top course being just in front of his feet. When a sufficient number of layers have been added rails are laid down, the driver connects up the steam-gear with the track-wheels, and the Titan rolls slowly forward a few paces over the blocks that a short time before were being dangled in the air.

— , Archibald Williams (1871-1934), , Harbours of Refuge, , The Romance of Modern Engineering, , 1904

1925 article (edited):

Giant Block-Setting Cranes

Mighty Titan Cranes

Another and larger type of crane use din connection with harbour construction work is that known as the "Titan", for the construction of which Messrs. Stothert & Pitt Ltd., of Bath, are famous throughout the world.

The Titan crane has a jib of the cantilever type and the load trolley runs along the upper boom, the whole jib turning on a live ring in a similar manner to that of the large jib cranes. Usually the Titan crane is steam operated, although cranes have been made for use with electric power where current is available.

Titan cranes are frequently constructed of such a size that they weigh 500 tons or more and they have been built to operate loads of up to 60 tons. Recently the writer saw under construction, at Messrs. Stothert & Pitt's works, a huge Titan made for the Union of South Africa for Harbour Construction at Table Bay, capable of handling a 50-ton load, and we hope at a later date to be able to give full particulars and to illustrate this remarkable crane, which will make a splendid subject for a Meccano model.

The Titan type of crane was evolved when the block-system of breakwater construction came into general use. ... The massive concrete blocks are cast in special yards near the scene of operations, and are wheeled on special trucks along the pier or gantry to a position near the crane.

This picks up the blocks and swings them out into the position in which they are to be fixed in the breakwater. The blocks are then keyed together ... in order that they may present a solid front to the devastating action of the waves.

Details of Titan's Mechanism

The Titan crane has the advantage of being mobile, so that it is possible to move it along the pier as the construction of a breakwater proceeds. Even more important is the fact that it is also practicable to withdraw it shore-wards for shelter in bad weather.

These cranes are capable of handling concrete blocks up to 60 tons in weight over a radius of 100 ft. or more. They do this by means of the long cantilever arm that is mounted on a turntable, which itself rests on a massive undercarriage. The under-carriage is mounted on flanged wheels, running on a special track and driven by means of crown wheels fixed on the inside of the bogie. A bevel gear, which meshes with the crown wheel, transmits motive power from the main engine mounted on the cantilever arm.

... Those of our readers who contemplate building a model of one of these Titan cranes will be interested to know that the motion may be perfectly reproduced in Meccano. ...

The Eight-Wheel Mounting

... The practice of driving four wheels out of eight on each side of the track is simply one of convenience and depends largely on the weight of the crane. In the lighter cranes it is not necessary to have four wheels to each bogie. ...

Massive Roller Bearings

The cantilever arm and superstructure of all Titan cranes revolves on a ring of live rollers, which in the case of a large crane may have a path of between 30 and 40 ft in diameter. The bearings are formed by a series of turned steel rollers held in position by a suitable frame and revolving on machined pathways between the upper and lower circular girders. ...

The whole of this revolving structure is centred by means of a large central pivot, consisting of a steel rod of considerable diameter. The revolving motion is transmitted from the engine, or – in the case of an electrically-operated crane – from the electric motor, which occupies a corresponding position on the opposite end of the cantilever arm to that from which the load is operated. ...

A Counterpoise Necessary

.. the weight of the engine or electric motor, as the case may be, helps to balance the load, but its weight alone is not sufficient and so a massive weight has to be introduced to act as a counterpoise. ...

Crab Requires 4-inch Steel Ropes

The motion from the engine is transmitted through a chain of spur-and bevel-gears, which finally engage in the segmental spur track, formed around the exterior of the roller path. In some cranes the gears are thoroughly protected from the weather by covering them with heavy metal casings, but this is not always found necessary.

As previously explained, the same engine drives the travelling motion of the crane in a similar manner by rod and gearing. The gears are engaged or disengaged by the engine-man, who, of course, also controls the hoisting and lowering of the load and the movements of the trolley. This trolley – which is sometimes called the "crab" and is also known as a "Jenny" – is drawn along the cantilever arm by steel ropes and a lifting rope 4" in diameter passes over it to the hoisting block. The lowering arrangements in the crane illustrated are controlled by a patent system and hydraulic brakes, which enable the heaviest weights to be lowered within limits of a fraction of an inch with absolute precision.

Titan cranes have been built by Messrs. Stothert & Pitt Ltd., Bath, for and used in the construction of some of the best known harbours in the world including Columbo, Madras, Gibraltar, Fishguard, Peterhead, Seaham, Tynemouth, Table Bay, Gisbourne, Vera Cruz, Antofagasta, Port Elizabeth, East London, etc.

— , -, , Giant Block-Setting Cranes: Their Work in Constructing Harbours and Breakwaters, , Meccano Magazine, , April 1925

Iconic status

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 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.

Meccano model revisions

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.

Meccano model plans

Plans for the model were published as Meccano Super Model No.4: Giant Block-Setting Crane.

External links

Originals

Meccano versions