Important Lockheed Innovations WHILST much interest will be aroused, at
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the forthIN coming Commercial Show, by the Lockheed-Gates Booster, a mechanical-servo gear, already described in this paper, there is a greater spice of novelty in certain other devices that the Lockheed Ifydraulic Brake Co., Ltd., Leamington Spa, is introducing.
Chief of these is the Bisector system of a combined mechanical and hydraulic operation, by which a transversely moving shoe expander obviates the need for crossshafts, etc. This is specially suitable for heavy commercial vehicles, where formerly a telescopic cylinder, placed externally, has actuated the shoes through a camshaft The Bisector functions on the wedge principle, and employs rollers of large radius, giving considerably higher efficiency thai a cam mechanism. A transverse cylinder imparts motion to the roller, Which moves between inclined faces, and an extension of the piston rod is coupled to the hand-brake system. A simple and easily regulated "click "type adjuster is provided. The Bisector is available in two sizes covering all classes of vehicle. Another development is the slotted-shoe brake assembly. With this arrangement the shoe is to some extent floating, and, in a simple manner, a self-energizing effect is obtained without any loss of smooth or progressive action. A running fit on the anchor pin, there is, for each shoe, a small square block, which fits in a slot in the shoe end. The slot is set at a slight angle, so that the spring pull holds the shoe off the drum. It is, nevertheless, free to move, against spring tension outwards, radially, at the anchor-pin end of the facing. This has been found to result in a 50 per cent. increase of braking torque.
Besides these, there are an automatic "hill holder," by which the foot brake, applied with-the vehicle stationary, cannot be released until the clutch pedal is depressed : a "tandem" master cylinder permitting the use of separate circuits to the back and front brakes, and an hydraulic control for engine throttle valve, which employs only a single pipe line, and gives instantaneous action and return.
We hope to describe these interesting and important new Lockheed devices more fully in an early issue.