P&M Motorcycles

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P & M 1915 770c V-Twin


The 6 h.p. twin P & M. with Lucas dynamo set. R. Transmission side showing enclosed chain cases

P & M 1914 Four-Speed Gearbox

A. Gear shaft.
B. Dog clutches solid with A.
C. Lay shaft.
D. Expanding gear mechanism.
E. High speed chain wheel.
F. Low speed chain wheel.

THE 6 h.p. P.&M. TWIN.

Four-speed Gear: 90° Engine of 770 c.c.; Protected Valve Springs and Tappets.

THAT Messrs. Phelon and Moore were bringing out a twin-cylinder model has for some time been an open secret, but it was not till early this year that the news leaked out that it would be fitted with a 90° twin. A short time ago we published preliminary details of an experimental machine which was a prototype of the model we are about to describe. This early machine had the standard two-speed gear, but the new type has four speeds, and several interesting details besides. Through the courtesy of Mr. R. Moore, we are able to give the first description of the new P. and M. in its final form.

One of our illustrations gives a clear idea of the engine, and since the carburetter has been removed a good view is given of the magneto and its cleverly enclosed drive. The latter is carried out in the following manner; A bevel fixed behind one of the timing wheels meshes with a crown wheel at the bottom of the vertical shaft, while the final drive is conveyed to the magneto by means of skew gearing. The aluminium case enclosing this is in two portions, held together by wing nuts, so that the tup half may easily be removed for inspection. The pinion on the magneto spindle, the end of which is tapered, is fixed by means of a combined nut and washer, which, when unscrewed, tends to withdraw the pinion, thus doing away with the necessity of prising it off. To detach the magneto, it is only necessary to loosen a screw, drop down the lower half of the cover of the gearing, undo the nuts, and remove the magneto complete with base plate.

Features of the Engine.

Owing to the cylinders, the dimensions of which are, by the way, 76 x 85 mm. (770 c.c), being arranged at an angle of 90 °, the balance is excellent, and, in consequence, the smooth running is all that can be desired.

Simple and ingenious shields are provided to protect the valve springs and tappets, which may be described as half tubes of spring steel which clip into position. These serve to keep dust from the tappets and prevent the oil from running on to the crank case, which the makers take an especial pride in keeping clean. Considerable ingenuity has been displayed in the design of exhaust lifter.

A pinion is keyed to the spindle attached to the arm visible in an illustration, which is connected to the Bowden wire mechanism. This pinion meshes with two wheels; one portion of the periphery of these is toothed and the other forms a cam, and these cams are forced up against the exhaust valve rockers when the Bowden lever is worked. Lubrication is effected by means of an Enots lubricator, which delivers the oil through the pipe just visible in the illustration to a point in the crank case adjacent to the front cylinder. Here the oil enters a channel which conducts a portion to the front cylinder, so that the piston picks it up at the bottom of every stroke, while the remainder is allowed to drip on the connecting rods. This method permits an ample amount of lubricant to reach the front cylinder, while the back one receives sufficient through splash.

The Four-speed Gear.

Next to the engine, the most interesting portion of the machine is the four-speed gear, which is arranged in a most ingenious manner. It is a clever combination of two well-known successful systems, of which one is an improved form of P. and M. gear, and the other an ordinary dog clutch two-speed gear box. The P. and M. gear has been improved by the introduction of wider expanding rings and wedge bars, which are now split so that any wear which takes place may be taken up by inserting thin correctly shaped metal plates.

A good idea of the arrangement may be gathered from the diagrammatic drawing. The shaft A, on which the dog clutch B slides, revolves independently of the chain wheels F E and both gear wheels, unless locked to either of the former by the expanding rings, or to either of the latter by means of one of the two sets of dog clutches. The first speed is obtained by sliding the dog clutch B to the right, which has the effect of lowering the ratios of the two P. and M. gears. If moved to the left the pinions in the gear box are idle, and the original P. and M. gear gives the higher speeds which are both direct. A pedal is used to bring the P. and M. gear into action, while a lever on the handle-bar is employed to engage the dogs.

It is interesting to note that no free engine position is given for the lever controlling the gear box. Such would be unnecessary, and may be explained more clearly by pointing out that the gear box merely serves the purpose of lowering the ratios of the P. and M. gear, and no matter whether the gear box is in operation or not the expanding gear serves as a friction clutch on either of its speeds for starting purposes. The gear ratios are 4 ½, 6, 8, and 11 ½ to 1 respectively.

In practice it is found that the fourth and third gears suffice for all ordinary districts, and that the second and first are really only for emergencies.

The 6 h.p. P. and M. is essentially a sidecar machine, and since no up-to-date sidecar combination would be complete without a dynamo outfit, provision for this has, of course, been made. The excellent Lucas installation can be supplied; this has already been described in The Motor Cycle, but the most interesting feature is the method of transmission. A spindle runs through the bottom bracket just behind the gear box on which two chain wheels are fixed, one driving the dynamo, while the other is driven by the chain from counter-shaft to rear wheel. This latter runs inside the chain case, while the former is also adequately protected, though its cover is not shown in the illustration.

The tank, which is of particularly pleasing design, holds two gallons of petrol and two quarts of oil, while large glass topped filler caps are provided. Owing to the engine forming part of the frame, the wheelbase of the 5 h.p. model is only half an inch more than that of the 3 ½ h.p., and it is worthy of note that the sidecar lugs form part of the frame. Kempshall 650 mm. x 55 mm. tyres are fitted.

Other portions of the machine to which we have not referred, such as transmission, forks, footrests, etc., follow P. and M. standard practice, and the finish, needless to say, is superb. Mr. Moore himself met us at Bradford Station with the original two-speed 6 h.p. model, and drove us back from the works at Cleckheaton in a most luxurious sidecar attached to the actual machine from which these photographs were taken. It started from rest on third speed, and took all gradients on top despite a very strong wind. The engine pulled remarkably well, and ran with a smoothness rarely found in petrol motors of this type.

In conclusion, we may say that this model is quite the best produced at Messrs. Phelon and Moore's works, and we prophesy a particularly rosy future for it.

The Motor Cycle, November 19th, 1914. pp557, 558.

6 H. P TWO CYLINDER MODEL. Price £81.18.0.


Equipment.-Every machine is fitted with stands, a carrier, tool bags and tool roll, number plates, inflator, born. oil can, and petrol squirt, and is tested on the road before being sent out.

Frame.-Sidecar lugs part of frame, which is designed to give lowest possible saddle position. Engine forms part of frame, P. & M. Patent No. 3516. Provision made {or Dynamo Lighting Set. Wheel base 54 in.

Wheels.-For 650 x 65 Voiturette tyres. Back wheel fitted with heavy butted spokes and two security bolts. Front hub fitted with removable spindle.

Engine.-90° Two cylinder type. 3 in. bore by 32 in. stroke (76 x 85) 770 c.c. Large interchangeable valves. Spring on covers for tappets and springs. Adjustable tappets. Correct distribution of oil to all parts. Pistons fitted with three rings. Especial attention bas been paid to oil retention and the oil releases discharge on to the chains. Shaft drive to magneto, automatically lubricated. Internal cam-operated valve lifter.

Forks.-Triple spring forks of the well-known P. & M. type.

Carburettor.- Specially designed Amac.

Ignition.-Magneto fixed between cylinders in an accessible and protected position.

Control.-Ignition, throttle, air. valve lifter and front brake from handlebars. Ail wires pass inside the bars. Engine starter and back brake operated by pedals.

Countershaft .-Speed Gear.-The well-known P. & M. two-speed gear in a larger sire and fitted with adjustable wedges in combination with spur gearing, operated by a dog clutch.

Gear Ratio.-Approximately. 4 1/2, 6, 8 and 11 1/2 to 1.

Mudguard.-Side flaps fitted the whole length of the front guard. protecting rider and sidecar passenger. Back guard is 5 inches wide and swivels to facilitate tyre repairs.

Transmission.-By two 5/3 x 1/4 in. chains to the countershaft, and one from the gear to the back wheel. Chain covers fitted with inspection plates. All chains are automatically oiled and chain covers can be easily removed in sections.

Weight.-285 lbs.

Starting.- By swivelling pedal acting directly on the main engine shaft. Stoutly constructed and adjustments provided for ail wearing parts.

The Motor Cycle

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