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A Quick-acting Centrifugal Clutch r' I NE of the difficulties in the design of

8th November 1957, Page 188
8th November 1957
Page 188
Page 188, 8th November 1957 — A Quick-acting Centrifugal Clutch r' I NE of the difficulties in the design of
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centrifugal clutches is that at the critical speed, engagement can be sufficient to cause wear by rubbing but not enough to transmit the drive. This intermediate position should be as transient as possible without giving rise to jerky engagement. A scheme with this object in view forms the subject of patent No. 782,924. (S.A. Francaise du Ferodo, 64 Avenue de la Grande-Armde, Paris.) As indicated in the drawing, centrifugal weights (1) swing about pivots (2), and as they rise press on cam faces (3) mounted on the pressure plate. Before full engagement can occur, the force of springs (4) must be overcome, and the combination of cam design and spring rate is such that the changeover period occupies only a small range of speed.

The chief feature of the patent is that the friction disc (5) has interposed in its assembly a crimped spring disc (6) to give a cushioning effect when full engagement is made.

AN ACCELERATION PUMP

PATENT No. 783,063 refers to engines using petrol injection and deals with a modification for giving an extra surge of fuel when the accelerator pedal is suddenly depressed. (Regie Nationale Des Usines Renault, 8/10 Avenue Emile Zola, Billancourt, Seine, France.) In the diagrammatic layout shown, petrol is normally delivered by a mechanically operated pump (1) to the injection pump (2) and thence to the separate cylinders. The injection pump

is quantity-controlled by intake suction through the pipe 3.

When the throttle is suddenly opened, the injection pump momentarily demands more fuel than the mechanical pump can provide. To supply this a flexible reservoir (4) is connected to the fuel line. Sudden pedal movement can compress this through spring 5 and supply the demand for fuel. Slow movement of the pedal is normally accompanied by a rise in engine speed and pump pressure, so that the operation of the reservoir has then little effect.

A FINISH FOR CYLINDER BORES

ACOMMON method of imparting a final finish to cylinder bores is by an abrasive honing operation, but this has two defects; it will not correct slight ovality or taper, and particles of abrasive are invariably left in the pores of the metal. This ultimately increases the rate of cylinder wear. An improved method of finishing is described in patent No. 782,859. (F. Anderson and The Austin Motor Co., Ltd., Longbridge Works, Birmingham.) The drawing shows the tool used. Six rollers (1) are caged in a member which is free to revolve between a pair of ballthrust races (2 and 3). The two cages are spaced apart by pillars (4) which

should not be confused with the rollers.

The drive is imparted by two cones (5 and 6) which are spring-loaded axially and tend to expand the rollers in a radial direction. When the device is placed in a cylinder and rotated, the rollers are pressed hard against the walls and create a smoothing and surface-hardening effect which is completely free from abra sive. The rollers are inclined at a slight angle to the vertical which has the effect of giving them a selffeeding action, A MECHANICAL SERVOMOTOR ASERVOMOTOR that derives its power from a rotating element on the transmission shaft and applies it to the brakes, forms the subject of patent No. 782,810. (K. and J. Eckhardt, 13 Lessing-Strasse, Leipzig, Germany.) The shoe carrier (1) is freely mounted on some part of the transmission shaft and is enclosed by a drum (not shown) attached to the shaft. When the shoes

are expanded by some means, a hydraulic cylinder (2) for example, the shoe carrier can swing through up to half-a-turn, the abutment 3 being its limit stop.

When the carrier swings it moves a lever (4) pivoted at the fixed point 5. As the lever pivots, it operates through a push-rod (6) to apply the main brakes.

The same action occurs in reverse, except that the lever is moved by singletooth gears abutting at the point 7, followed by two more as shown at 8 and 9. An abutment (10) limits the swing.

POWER-ASSISTED HYDRAULIC , BRAKES

PATENT No. 782;629 shows a braking system in which the pedal movement causes an obstruction to be applied to a fluid circuit, thus setting up a servo pressure which is applied to the master cylinder. The novelty of the scheme. is that only the front brakes are worked by the master cylinder, those at the rear being operated by pump pressure, (L. Coatalen, 7 Rue Lesueur, Paris.) • The drawing shws the layout in which a pump (I) circulates liquid through a control valve (2) and a return

pipe. The valve is pedal-operated, and when it is moved to restrict the flow an increased pressure is created and applied to the master-cylinder (3) for the front brakes.

The rear brake supply is branched off from the pump delivery at a T-junction (4). This contains a venturi which, when the liquid is passing freely, creates only a low pressure or even a slight suction in the rear brake pipe.

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Locations: Birmingham, Leipzig, Seine, Paris

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