Patent GB-361524-A (GB)
Title: Improvements in apparatus for testing the brakes of vehicles
IPC: G01L5/28
Filed: 1930-10-15
Abstract: 361,524. Testing vehicle brakes dynamometrically. HEENAN & FROUDE, Ltd. and WALKER, G. H., Worcester Engineering Works, Worcester. Oct. 15, 1930, Nos. 30808/30, 33338/30, and 4390/31. [Class 106 (ii).] Comprises a device for testing the brakes of road vehicles which indicates directly the efficiency of the brake, that is, the ratio of the force exerted tangentially on the rim of the wheel to cause it to rotate and the weight supported on that wheel. A single test unit is shown in Figs. 1 and 3. A roller 1 is mounted by ball bearings 14, 15 on a shaft 16 the ends of which are fixed to cranks 2 the pivots 17 of which are carried on ball bearings 18 in the upper ends of compensating links 3.which are pivoted to the frame 12. The ends of the shaft 16 are extended to engage in normally horizontal radius rods 4 mounted on pivots 5 in projections 6 of the frame so that the rod 16 is constrained to move in an approximately vertical direction. The weight of the roller and shaft is counterbalanced by springs 7. The fluted roller 1 is driven by a crank handle 22, shaft 21 and gear 20, 19 and power is transmitted to a similar roller under the other vehicle wheel on the same axle by a chain gear 23, 24, 25 and shaft 26. A pointer 8 attached to the crank 2 moves over a dial 10 mounted on the pivot 17 and prevented from rotation by a link 9. An independent pointer 11 moved by the pointer 8 indicates the maximum reading attained in the test. At the beginning of a test the axis of the roller is vertically above the line joining the pivots of the links 3 which are vertical, but on application of torque to the handle the brake being on, the reactionary torque causes the link 3 to take up a position inclined to the vertical and the angle of the crank to the vertical measured by the movement of the pointer over the dial 10 indicates the efficiency. The brakes when under test are applied by a pedal depressor having an indicator to show the pressure exerted on the pedal. By suitably proportioning the links and gearing the graduations of the dial 10 may be made approximately uniform. Any suitable gearing may be used and a motor carried on the crank pivot or link 3 may be substituted for the hand drive or a portable motor may be used. Clutches &c. may be fitted to allow of one brake being tested at a time. In a second form two testing units are mounted on an underframe sunk into the ground and the front and rear pair of wheels are run on to them and tested in turn, a winch being provided for hauling the vehicle into position and retaining it while under test. Instead of the device being sunk into the floor a platform may be provided on which one pair of wheels may rest while the other pair is on the drums. Ramps are arranged to facilitate entry and exit from the device. In a further form, one set of drums is carried on a fixed frame and the other on a trolley the space between being bridged by girders one end of which is attached to the fixed frame and the other supported by the trolley. The first Provisional Specification also describes a form in which the front or rear wheels are run on to a pair of drums carried by a frame or trolley the forward drum of a pair being carried in an auxiliary frame pivoted or slidable so that the drum pushes the vehicle wheels vertically above the axis of the rear drum. When the brakes are applied and a turning movement imparted to the rear drum, the resultant force due to torque reaction and the weight carried by the wheel causes the rim or tyre of the wheel to leave the surface of the forward drum. The angle made with the vertical by a line joining the axis of the rear drum and axis of the wheel at this time denotes the efficiency of the brake.