Horizontal Linear Actuator

Linear actuators are widely used in industry for moving parts, or as an integral component of a machine such as an industrial robot. The Meccano model illustrated is of sturdy construction, which will withstand quite powerful bending or twisting forces. It is also designed to be free from vibration and is tight in its bearings, with minimal gearing backlash, features essential in robotics.

The Actuator consists of two parts, a static housing which provides bearings for the moving part with an attachment for the motor, and a moving section.

The moving section is a built up H-shaped girder. Two pairs of 9.5" angle girders are bolted together by their round holes to form U-sections facing away from each other. These are bolted to each other using two overlapped 9.5" flat girders on each side. A 6.5" rack strip is bolted to the side of the girders, separated from them by two washers on each bolt, and this meshes with a 0.5" pinion on the motor shaft.

Each side of the housing is made from two horizontal 3" flat girders, joined together by vertical 1.5" flat girders. They are connected together at the top by two 2" angle girders joined by a 2" flat girder, with a similar arrangement below. Eight 0.5" pulleys are used as rollers for the moving section, and they are fastened in pairs to four 2" rods, the bearings for which are the free corner holes of the housing. The moving section is slid into the housing. Washers and collars are used where necessary to allow the pulleys to track on the free flanges of the moving section.

A 0.5" pinion mounted directly on the motor output shaft meshes with the rack strip on the moving section. The motor is a Richards 6 speed motor with integral epicyclic reduction gearbox set to the highest 60:1 reduction setting. Two overlapped 1.5" flat girders are bolted to the base of the motor, and 2.5" girders are attached to them. This assembly is then attached to the side of the housing via 1.5" girders bolted to the housing, reinforced with a corner bracket, above and below.

For feedback to a central processing unit such as a Programmable Controller or Computer, there is room to attach two limit switches to the inside of the housing, and each could be tripped by a small screw attached to the moving section. Other devices such as proximity sensors could be used.

Copyright Michael Adler

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