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Building Model of Six-Axle Link-Belt 268 Mobile Crane.

By Blake Huffam

 In the following article, Club member Blake Huffam of San Gabriel, California, describes the construction of his model of the Link-Belt HC-268 six-axle truck crane which was illustrated on the cover of the First Quarter 2002 issue of the Newsletter.

        

The model Link-Belt truck crane is built to a scale of 1:24. It was established by the dimensions of the wheels and tires available in Meccano, braced girders to fit the dimensions of the boom and spaces needed for the winding drums, motors and drive gear. The overall dimensions were then scaled up from pictures of the crane, and the machinery was then designed to fit the spaces and perform the movements of hoisting, rotation, etc.

The dimensions of the truck frame (chassis) and platform were established with the wheel and tire, P.N.187c, from Multimodel 20 Set and Junior Action Trooper Set No.7008, obtained at big discounts from The Hobby Shack.

The tires needed "pressurizing" to support the weight of the crane and this was achieved by stuffing them with styrofoam packaging peanuts.

The three front axles were mounted to the underside of two perforated strips on each side, spaced from the frame of the truck horizontally to act like two long flat springs supporting the three axles.

The steering is simply constructed using P.N.11 double brackets, strips, pins and stub axles to take the wheels. Steering utilizes a " pinion engaging a 1" gear (P.N.27a), for a 1:3 ratio from the steering wheel.

The truck platform or bed is 6" wide and 28" long. The rear three-axle bogy is mounted to the truck frame at the center axle, allowing limited vertical movement of the leading and trailing wheels, controlled by Meccano shock absorbers, P.N.120d.

The reinforced base for the geared roller bearing mounting the crane, is constructed utilizing flanged plates, P.N.52, held in place with angle girders attached to the main frame of the truck.

The outrigger stabilizers are slung under the frame and slide out to an overall width of 11". They use sleeve pieces, P.N.163, the " flanged wheels (P.N.20b) and the 1" contrate gears (P.N.28) for pads.

The crane base supports the main-frame center of the crane which in turn houses the four winding drums. It is 2" wide. The main boom and hoist frame are pinned to trunnions at the forward part of the main frame.

                         Winding Drums

The winding drums (1) raise and lower the boom; (2) raise and lower the jib; (3) operate the main hoist; and (4) operate the auxiliary extension lift.

The rear section representing the counter-weight in dark blue color, houses the battery boxes and motor controls appearing vertically above. The batteries serve well as counter-weights.

The two-inch-wide space on either side of the crane's main frame house the four motors and reduction gearing to each winding drum. Worm drives control the loads at the hook and boon lifts. A fifth motor behind the control cabin actuates the geared roller bearing, P.N.168, for sluing control.

                         Battery Packs

Motors, Meccano motor P.N.770, are used with four battery packs for the main drives and two battery packs for the remaining drives. The counter-weight housing structure is easily removed by lifting two vertical pins. Similarly easy removal of the side panels expose the batteries and the motor drives.

Connected to the boom and main frame are telescoping arms which represent the gear on the crane, with safety relays indicating safe operating limits.

                       Junior Set Parts

Junior set parts used include the tool boxes on either side of the truck platform, the main hoist hook, the radio antenna mounted on the side of the truck cab, and the tires which are now available in the 30, 40 and 50 multi-model sets.

The cables holding the boom and jib are wires encased in green plastic with the same diameter as Meccano axles and fit snugly in Meccano bosses.

The long hoist ropes were also purchased at a hardware store and were departures from pure Meccano. The miniature men seated in the operating cabins are Meccano from the Junior sets and are to scale.

Colors are zinc trim and structure, red flashing, and yellow, blue and red panels. 

 

Last Updated: August 9, 2004