housings, handle covers, switch assem- blies, brush holders and caps, brushes and internal assemblies are identical, providing one set of main spares to save time and storage space where drill capacities from 5/16 in. (7.94 mm) to 1⁄2 in. (12.7 mm) are required.
Three two-speed models, HB 237, 238 and 239, are in the range, their motors rated, respectively, at 300W, 260W, and 300W. Respective spindle speeds under full load are quoted as 1100/425 r.p.m., 1200/429 r.p.m. and 1100/429 r.p.m.
The drilling capacity in steel of the HB 237 and 238 is 3/8 in., HB 237 having a 3/4in. (19mm) capacity in hardwood and the HB238, 5/8 in. (15.9 mm). Approximate equivalent figures given for HB239 drills are 1⁄2 in. (13 mm) in steel and 25/32 in. (20 mm) in hardwood.
Model H137 has a drilling speed of 1700 r.p.m. under full load, a motor rated at 220W and a 5/16in. (7.9mm) Jacob's type chuck. A percussion drill,
HB237 electric drill
PSB137, completes the range of five. Weighting 7 lb. 5 oz., its 300W motor delivers 6,600 strokes per min. under load at a drilling speed of 600 r.p.m. Its drilling capacity in concrete is 1⁄2 in., in brick 3⁄4 in., and in steel 3/8 in.
LIGHTING CONTROL
Designed by Synchro Develop- ments (London) Ltd., 54 Queen Anne Street, London, W.1., the Weri- Lux electronic light dimmer can re- gulate lighting loads up to 400W from off to full on. It is controlled by a white-plastic knurled thumb wheel set within a small face plate, also of white plastic.
Each dimmer comprises solid-state silicon-controlled switch and drive cir- cuity, an edge-type potentiometer in- corporating an on/off switch, a separ- ate safety fuse and radio interference suppression. The major components are potted in epoxy resin, to give extra protection and promote heat dissipation, and the whole assembly is housed in a circular plastic wall box measuring 63mm in diameter by 40 mm in deep.
Square or circular face plates with
Weri-Lux electronic light dimmer
overall dimensions of 80 and 78 mm respectively can be provided and a common projection of only 10 mm from the wall surface to the outside edge of the thumb wheel is available. On multiple installations, the plastic wall boxes slot together to facilitate handling and ensure even spacing.
LAMP
The Wessex lamp introduced by Wessex Engineering, 57 High Street, Farehem, Hants., U.K., accepts any bulb size up to 150V, sealing it within a protective assembly consisting of a clear, vapour-proof wellglass and an outer metal cage.
Supplied with a wondering lead, the lamp is designed for use in areas where the heat from a bare electric bulb might ignite inflammable vapours. It can also be used in general building applications.
In addition to the guard and well- glass, the body of the lamp incor- porates a metal-alloy cowling mounted at the end of an 18in. long tubular steel rod. The cowling houses an elec- tric socket for the bulb, the rod acts as a handle, and rubber-tipped screw fitting at the end of the guard cage clamps the wellglass against a pressure seal around the inside edge of the cowling.
Wessex lamp
Measuring 40 ft. (12.192 m) long and fitted with a 13A rubber plug, the three-core plastic-sheathed flex passes up the hollow metal handle and into the fitting through a vapour-proof gland. A 3ft. (914mm) metal chain en- ables the lamp to be suspended at any angle.
Overall dimensions are 2 ft. 7 in. (787 by 280 mm) and the total weight is 14 lb. (6.4 kg).
MEASURING INSTRUMENT
A measuring wheel marketed by Protasil Ltd., 35-39 Maddox Street, London, W.1. makes tapeless measure- ment possible on any area. Known as the Measure Master, the instrument consists of a 2in. (51mm) diameter rubber-rimmed wheel on a handle and connected to a digital counter. It gives readings up to 1,000 ft. in feet and inches.
When the wheel is pushed by the
Measuring wheel
handle across the surface to be mea- sured, the counter gives the distance travelled. Five threaded handle exten- sions measuring 7 in. each allow mea- suring beyond the operator's reach or without stooping. Without extensions, the instrument is 81⁄21⁄2 in. long, and comes in a plastic wallet.
FLUORESCENT LIGHTING
The first of a redesigned range of Heyes flameproof fittings accepts a 5ft. (1,524m) fluorescent tube. This version differs from previous models by housing the starter gear within an oval-section casing at the end of the tube instead of a separate box on top.
Made of grey-enamelled die-cast aluminium, the gear housing attaches to the ceiling by means of a chromium- plated steel bracket. A flameproof glass cylinder protects the fluorescent tube as before, and a simple fixing with a knurled release nut supports the fitting at the opposite end from the gear housing. Unfastening the release nut enables the whole unit to be pivot- ed downwards around the pinned con- nection in the steel bracket for re- lamping.
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Far East BUILDER, August 1969