95. Chain Drive.-The PS-1 sound head is driven through a Morse silent chain. When the chain is in good operating condition it will run silently without slipping. Regular lubrication (at least once a week) with a heavy engine oil (such as Mobile B) or cup grease will help materially to keep the chain in good condition. Should it be necessary to remove the chain for any reason, make sure that it is replaced correctly. Be sure that the arrows stamped on the side of the links point in the direction the chain is to run. Do not use for lubrication any grease containing graphite or other solid matter.

96. Lubrication of the Type PS-1 Sound Head.-Figure 64 shows the oiling points on the operating side of the PS-1 sound head. Four oil ducts, fed by a trough located near the top of the sound gate, supply oil to the constant speed sprocket and take-up sprocket, and also oil two bearings of the sound head drive mechanism. The sound gate guide rollers and the sprocket pad rollers should be oiled once a day as follows:-Dip the end of a tooth pick in a good grade of light machine oil and apply the oil which adheres to the tooth pick to the bearings of the guide rollers, and to the oil holes in the pad rollers.

The drive side of the PS-1 sound head should be lubricated as follows:-The oil cup on the shaft of the chain drive sprocket wheel should be packed with cotton waste, and the waste should be kept saturated with a good grade of light machine oil. An oil pipe, terminating a little to the right of the sprocket wheel referred to above, should receive one drop of a good grade of light machine oil once for every two hours the machine is run. See Figure 63.

Different types of projector drive motors are used with this sound head, the lubrication of which was covered in Chapter III.

The drive chain should be lubricated once a week as described in section 95.

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