> > > >

1947-48 Theatre Catalog, 6th Edition, Page 347 (333)

1947-48 Theatre Catalog, 6th Edition
1947-48 Theatre Catalog
1947-48 Theatre Catalog, 6th Edition, Page 347
Page 347

1947-48 Theatre Catalog, 6th Edition, Page 347

circular cross section which in turn fits a machine bore in the soundhead casting. The flywheel shaft runs on precision ball bearings, as it is essential that it should impose the minimum load on the film. The two sprocket shafts run on oilite bearings as they are driven by the motor.

To cope with different voltages and periodicities, it is necessary to use a number of different types of motor. For the normal British supply of 190 to 260 volts, 50 cycles, a 1/; -hp. capacitator start motor is used, but this is supplied in three different models wound to suit respectively voltages of 190 to 210, 215 to 235, and 235 to 260. Externally and in all dimensions, these three motors are identical. The motor is mounted in front of the soundhead with its shaft horizontal and parallel with the sprocket shafts of the soundhead. The drive from motor to soundhead is by twin, short, endless, canvaseand-rubber V-belts. The ratio of belt pulleys on motor and soundhead is such that the motor speed of 1,470 rpm. is reduced to a speed at the soundhead of 990 rpm.

The motor itself is resiliently mounted, and is held to the stand by four set screws passing through elongated holes in the motor base. The set screws enter tapped holes in the stand. The motor and the belt drive are protected by a quickly detachable, louvered cover, through which an inching handle projects on the operating side.

For (SO-cycle supplies, the same motor is used, With an appropriate increase in the reduction ratio of the belt drive. For 40-cycle supplies, a special 40-cycle motor is used, and the reduction ratio

THE GAUMONT-KALEE 21 PBOIECTOR, seen from the operating side, is totally enclosed. The streamlined appearance and the flush, tight-fitting doors to the arc lamp, projector mechanism. soundhead, and magazines are noted. Arc controls are on a panel at the rear of the lamphouse.


on the belt is decreased. For 25 cycles, a special 25-cycle motor is used, which, having two field poles, rotates at approximately the same speed as the standard 50-cycle motor. For 30 cycles, the 25-cycle motor is used, with an appropriate adjustment to the belt drive ratio.

For special studio requirements, a 3-phase synchronous or an interlock motor is used, and as truly synchronous speed must be maintained on the film sprockets, gear drive takes the place of belt drive. Where, as in theatre practice, only a close approximation to talkie speed is required, belt drive has everything to recommend it. It simplifies the layout, is silent and long-lived.

The driving pulley of the soundhead rotates with the main driving pinion, to which it is held by three screws on a heavy stationary layshaft, hardened and ground. This layshaft is very securely held, for an inch and a half of its length, in a machined bore in the soundhead casting. The layshaft is inserted from the non-operating side into the machined bore, its accurate location being determined by a shoulder on the shaft, and held in position by a nut on the operating side of the soundhead, into which the threaded end of the shaft just protrudes. The pulley and pinion are retained on the layshaft by a washer and large hexagonal retaining screw. The retaining screw is bored and tapped for a Rotherham-type oiler. The pulley and pinion are oilite hushed. The Rotherham oiler communicates with an annular groove in the shaft, from which the oil reaches the bushes. A guiding idle sprocket for the chaine drive to the

bottom take-up is also carried on the layshaft.

In addition to this layshaft, there are only two other shafts to carry the rest of the gearing, including the gear which drives the projector and the chain-wheel which drives the bottom take-up. These remaining two are the sprocket shafts already referred to, carried with their bearings in detachable housings. The shafts themselves are hardened and ground. The shaft is on bearings with a center annulus which acts as an oil reservoir. The housing has a large D-shaped flange on the operating side, and this flange carries the lay on roller, spindle and bracket, and the film stripper. The complete housing is inserted into its bore from the operating side of the soundhead, and secured by three screws which pass through the flange into tapped holes in the soundhead. The spacing of the three screws make it impossible to fix the housing in anything but the right position, and the location of lay on roller and stripper on the flange ensure permanent alignment of these components with the sprocket.

These two assembles of shaft, bearings, and flanged housing carrying lay on roller and stripper are identical and interchangeable, although the stripper, according to whether the assembly is used in the upper or lower position, adopts one of two different positions. Provision for these two positions is very neatly provided for by a small key, integral with the stripper, which engages with one of the two key ways. In either position the stripper is positively held at the correct angle.

The two film sprockets are not the

ON THE NON-OPERATING SIDE. the gas cylinder (seen beside the upper magazine) for fire-fighting can be noted, as well as the large View window showing the lubrication system. The color scheme is in middle-stone picked out with white lines. maroon, and with the bright parts chromium-plated.
1947-48 Theatre Catalog, 6th Edition, Page 347