> > > >

1953-54 Theatre Catalog, 11th Edition, Page 285 (249)

1953-54 Theatre Catalog, 11th Edition
1953-54 Theatre Catalog
1953-54 Theatre Catalog, 11th Edition, Page 285
Page 285

1953-54 Theatre Catalog, 11th Edition, Page 285



Fig. 3-8 good joint must be tight enough in

order that the resisting torque of the positive

contacts on carbon "A" be smaller than the

torque necessary to have carbon "B" slip into carbon

necessary to have carbon HB" rotate by slippage into carbon ttA" (Fig. 2b) should be greater than the resisting torque offered by the positive contacts to the rotation of carbon 0A" (Fig. 3).

Physical Requirements of the Joints

It is also necessary that there be no interruption between the core and shell of carbon EA" and the core and shell

3 '5 Pig. 4-Two machined carbons ready to be pressed into each other are shown below.

of carbon ttB." Figure 5 shows a tight joint. The carbons move in the direction of the arrow. The tapered surfaces of both carbons apply closely against each other. Between the shoulder "Sit of carbon ttAii and the end ttE" of carbon "B" (both in shell material) the distance must be Very small. Between the bottom tibi, of carbon "B" and the tip 0t" of carbon ttAil there is also a gap which should be as small as possible. If these two gaps could be reduced to zero, the quality of the joint would be perfect. When the rod thus formed by the joining of the two carbons progresses towards the arc, carbon ttA" is first consumed. then both carbons are consumed simultaneously for a short period, fol


Fig. 5-Section ol the two joined carbons.

lowed by the consumption of carbon "Bil alone. Figure 6 shows these situations. The two carbons move in the direction of the arrow.

Situation 1) shows the crater entirely in carbon HA."

Situation 2) shows the crater partially in carbon HA" and partially in carbon illiW

Situation 3) shows the crater in carbon Hliii only.

The transition from one carbon to the next is a continuous process which lasts one minute. When the carbons are well machined and when the gaps (Fig. 5) are


1/64 inch or less, it is impossible to detect that one carbon has been replaced by another.

Continuous Feeding

of Negative Carbons

The consumption of negative carbon is much smaller than that of the positive carbon. It is generally possible to operate

Fig. @fLocation of crater at positive carbon when two joined carbons A and B move toward arc.

a very bright arc lamp for a period of one hour and a half without recarboning the negative carbon. However, if continuous operation is desired for several hours, continuous recharboning is required.

The arcing point, on the disk, is located on the line which joins the center ttO" of the disk to the center "Cit of the tip of the positive carbon. The disk revolves slowly, making one revolution every three minutes. Each revolution reduces the radius of the disk by 2/1000 inch to 4/1000 inch, depending on the current, and the disk keeps its true circular shape. A mechanism moves the center so" slowly towards "C," in order to keep a constant gap between the arcing point and the positive carbon. With a current of 200 amperes, an eight inch diameter disk can last several hours before having to be replaced.

Magazine Mechanisms

Mechanisms have been devised to feed the carbons from a magazine and join them automatically. The mechanism must operate very smoothly because the carbons are fragile, especially when they have been machined.

We have built several types of mechanisms which feed the arc lamp with positive carbons and join them automatically. They assure an automatic continuous operation of the lamp.

Figure 9 is a simplified diagram of an arc lamp in operation with a joining mechanism. Carbon ttA" has one end in the arc and is being consumed. It slides between the positive contacts and it is fed into the are by the action of the feed rollers ttR." The tip it" of carbon ttA" is in position (1) in Fig. 9. A few

Fig. 7-This is an artist's conception .01 an arc in which both electrodes comprise joined arcs.

TML may

9057," EAR BON




Fig. BeView of an arc in which the positive electrode is made with ioined carbons and the negative electrode with a graphite disk.

seconds later, it will reach position (2). At that moment carbons uB," ttC" and ttD" will be pushed vertically upward under spring action. Each of the carbons will occupy the position that the preceding one occupied before the ttpush." As soon as carbon ttB" has reached the position where it is in line with carbon ttA," a pusher thrusts carbon ltBii toward carbon ttA" and joins them together (joining action). A precise pressure must be applied on the joined carbons to assure a tight joint.

A few minutes later the joint reaches the arc. Thereafter carbon 0B" is consumed alone. When the tip of its end reaches position (2), carbon ttCiy is pushed vertically upward and the same cycle is repeated.

Applications of the Automatic

Continuous Operation

Several applications for automatic continuous operation have been made in arc lamps which must operate for several hours without interruption or which are located in spots which the operator can

? seams ACYWN T

Fig. 9-Schematic View ot.a feeding and joining magazine mechanism arc lamp.

not reach during the operation. This is the case with searchlights used by the Armed Forces. Figure 10 shows a 200 amperes arc lamp with automatic continuous operation.

The mechanism which assure the feeding and the joining of the carbons is built in these are lamps and is not an additional piece of equipment attached to a standard arc lamp. The mechanism is simple and contains several features for which patents have been applied. It has not been used for projection lamps yet, although it is expected that the use of 3-D films and very large screens will induce the theatres to use more powerful projection lamps and therefore to use mechanisms which will assure longer operation without recarboning.
1953-54 Theatre Catalog, 11th Edition, Page 285