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Although
Hewitt & Topham Ltd
possesses a wealth of skill and experience in the general precision engineering fields, the company specialises in the manufacture of custom made gears, including spur gears, helical gears, bevel gears and worm gears, and supplies the subcontract and spares market both nationally and internationally.
The company manufactures custom made gears to customer designs and/or samples in a number of different materials. All the recognised types of gears are continually in production, from 2.5m in diameter down to 6mm diameter.
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Spur Gears
Spur gears are those that have the teeth cut parallel to the axis of the shaft. A cross section of the tooth is identical for both size and shape along the entire
length.
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Single Helical Gears
With helical gearing the teeth mesh gradually and at no period is the full width of any one tooth completely engaged.
Double Helical Gears
Double helical gears give the same advantages and smoothness as single helical gears, but with the added value of a much greater strength in the contact of the teeth and no side ways force.
Bevel Gears
The majority of bevel gearing made is for shafts at right angles to each other, and with the apex of the pitch cones lying at the same point. The size of the tooth diminishes as the cone apex is approached; the contour of the tooth also alters as the tooth size decreases.
Spiral Bevel Gears
As the teeth overlap and give a continuous pitch line contact with more teeth in mesh at any one time, the load is transmitted without shock or sudden impact loadings on the teeth which gives rise to noise and vibration.
Worm Gears
A wheel gear always accompanies these gears. Worm gearing is another method of driving two shafts the axes of which normally lie at right angles to each
other. The usual driving member, the worm, may have either a single or multi-start thread.
Racks
Rack gears have their teeth cut on a flat surface. As there is no curvature on the pitch line, teeth cut to a basic
in volute tooth form have straight sides.
The teeth may be cut at right angles to the direction of travel as for a spur gear, or inclined if to mesh with a helical gear.
Serrations
Internal and External In volute Splines
Internal and External Straight Splines
Chain Wheels (Sprockets)
Ratchets
ANCILLARY OPERATIONS
Broaching , Slotting, Screw cutting (Acme, square and 'V'), Turning, Milling,
Grinding, Drilling, Laping, Tooth Rounding, Keywaying
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http://www.hewitt-topham.co.uk
