Gramophone Motors

Radio Record, Volume III, Issue 43, 9 May 1930, Page 7

Gramophone Motors

Care of the Spring So many of us, one. fears, -get into the habit of regarding winding the radio gramophone as an affair of evil, and consequently of treating it as such. The result is, of course, that the unoffending mainspring of the machine regularly becomes, as a matter of practice, subjected to a series of the most convulsive and violent moveiments during the process of. winding up. | The average single spring of a smallyhotor is enclosed in a steel case, and, fas such, constitutes the drive of a "sin- %. gle spring" motor. Double and triple spring motors have their individual springs arranged in tandem, but, névertheless, in nature the springs are the same.

aleeteets _ Springs are manufactured in varying lengths, breadths, and tempers. Other factors being equal, the spring . Strength available for driving the motor depends upon the thickness, length, breadth, and temper of the steel band. For a given cross section and temper of material, the longér the spring, the less intense is its effect. If a spring is wound up jerkily it is subjected to a series of strains which effect it wunequally throughout its length. Continuance of this practice results in the spring being weakened in parts. Consequently, a spring in this condition can never maintain a constant number of turntable revolutions per minute, and so’ the performance of the radio-gramophone decreases in efficiency. Always Wind Steadily. & winding. the handle of the machine should be turned with a gentle and nn

steady motion. The winding speed need not be at all slow, but-all semblance of jerkiness should be avoided if the life of the spring and its pristine éfficiency is valued. It is best not to wind the spring to its maximum extent, for by so doing not only may the spring become unhooked within its case, but the tendency will be for the tightly compressed spring coils to squeeze out the tubricant between them. Pxamination of the spring cases of motors which have continually been wourd up to their

maximum extent will often reveal the presence of squeezed-out grease on the exterior. of the case. On the other hand, too, the radiogramophone motor, after use, should never be allowed to run right dow to the bottom. Always stop the oto) just before it runs out. Otherwise the spring may become so loose that it may become unhooked. It is bad practice to assist the turntable of a radio-gramophone to attain its full speed after the motor has been turned on by giving it a push with the fingers. Injuring the Governor. TPHIs injures the governor springs, and in no way assists the mainspring. Nor should the turntable be stopped very suddenly after the record -has been played. It is -best to stop the turntable very gently with the fi: gers before applying the brake of the

machine. For this reason, automatic Stopg fitted to machines have to be extremely good ones before their use is to be recommended. Finally, if your machine will run for more than one or two records, avoid the practice of rewinding after. each record has. been played. Such a habit results in only one portion of the spring being used. The consequence is that this latter portion eventually undergoes partial fatigue, while the unused portion remains fresh.