From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Article from 'Motor Cycling' magazine detailing a new P. and H. lighting dynamo with an innovative slipping-clutch method for regulating output.
| Identifier | ExFiles\Box 61\2\ scan0130 | |
| Date | 10th September 1919 | |
| 434 MOTOR CYCLING September 10, 1919. PULLEY RUNNING ON LARGE BALL RACE FERODO FACED PLATE CLUTCH. Side and end elevations of the new P. and H.{Arthur M. Hanbury - Head Complaints} lighting dynamo. THE LATEST DEPARTURE IN LIGHTING SETS. Ingenious Method of Regulating Output—A Neat Handlebar Switch. MESSRS POWELL and HANMER, of Birmingham, well known as the manufacturers of acetylene motorcycle lamps, have turned their attention to dynamo electric lighting, and have now produced a motorcycle set. As will be seen from the illustration, the dynamo is of very neat design, without any more projections than are absolutely necessary. The armature is carried on ball bearings of ample size, and thrust washers are provided to take end strains. Oil retainers are fitted to the bearings to obviate the necessity for outside lubrication. The most novel feature of the generator is the method of regulating the electrical output, which it is, of course, necessary to keep as constant as possible. Messrs. Powell and Hanmer have accomplished this by means of a slipping-clutch device, which operates in the manner described below. Reference to the drawing will perhaps assist. The pulley by which the dynamo is driven is mounted on a ball race on the armature shaft, and the outer side of this pulley forms one plate of a friction clutch. The other member of this clutch is a Ferodo-lined disc, in the centre of which, and sliding over the armature shaft, a squared boss fits. In this boss a spiral groove is cut, and a pin fits through this groove and a hole in the armature shaft. Thus, on a turning movement being applied to the boss, it will move along the armature shaft within the limits of the pin working in the groove, and, carrying the Ferodo-faced disc with it, will bring the two clutch members together and so drive the pulley. This is its normal position, and it is held so by a coil spring, the inner end being attached to the boss and the outer end to a fixed cover which is secured to the end of the armature shaft by a screw and pegs. Thus, the pulley drives through the friction clutch, the sliding boss, and the pin through the armature shaft. Now, the operation is that at any speed beyond that at which the pre-determined output is given off, a drag in the armature is set up, equal to that of the set tension of the spring. Thus the driving pin pushes harder against the spiral groove in the boss and causes the clutch to slip. The amount of movement necessary to cause this is infinitesimal, approximately .002 in., and thus the action of the clutch is more in the form of a vibration between the Ferodo disc and the pulley. The switch box which incorporates an ampere-meter, At a demonstration of this method of regulation the dynamo was connected to an electric motor which was driven at continually varying speeds between 600 and 3,000 r.p.m., and no variation could be noted in the volt- and amp.-meters from the normal output of 12 volts 8 amps. This means that, should, for any reason, a battery be out of action, the lights could be run from the dynamo only—a very desirable feature. An automatic cut-out, which disconnects dynamo and accumulators when the machine is at rest, is fitted in a box on the top tube. Another very neat point of this set is the switch box, which is placed on the handlebar. The body is of aluminium, and circular in shape. Mounted in its face is the ampere-meter dial, the rim surrounding this forming the switch. There are four positions — “off,” “charge,” “full lights,” and “dim”— any one being obtained by turning the rim. This is undoubtedly one of the neatest electric lighting sets yet produced, and should be deservedly popular with motorcyclists. Details of the driving pulley Driving Pin Operating Cam Spring Housing Spiral Spring Fixing Screw Driving Pegs Armature Shaft 'Ferodo' faced Plate Clutch Pressed Steel End Cover B16 | ||