GB563563A - Improvements in testing stands for measuring the propeller torque of aircraft engines - Google Patents

Abstract

563,563. Dynamometers. AKTIEBOLAGET AEROTRANSPORT. Dec. 12, 1942, No. 17702. Convention date, Dec. 15, 1941. [Class 106 (ii)] A testing stand for measuring the propeller braking torque of an aircraft engine comprises a mounting member 1 for the engine which is connected to the beam 3 of a balance by means of two links 2 forming opposite sides of a parallelogram linkage and transmitting to the beam the reactive torque corresponding to the propeller torque, and is characterised in that the two links 2 include elastic connecting members 7 which permit small rotary movements of the links relative to the mounting member 1 and the beam 3 respectively at the connecting points, which movements are completely free from sliding friction, and that the beam co-operates at one end with a force-absorbing member permitting small deflections and is connected to a measuring instrument 28. The plate 1 is connected to a rigid frame 6 by four horizontal links 4 and one lateral link 5, all incorporating elastic members 7, comprising a rubber ring vulcanized to steel sleeves, Fig. 3 (not shown). The beam 3 is elastically pivoted at 13 and its movements are opposed by two helical springs 16, 17 and a dashpot 23. Movement of the beam is transmitted by a rod 26 through a hydraulic vibration suppressor 29 to a lineardimension dial gauge 28. In the modification shown in Fig. 5, -a strong spring 34 presses on the beam which carries a cover-plate 33 opposing the flow of fluid from the inside to the outside of a hydraulic pressure chamber 32 under the influence of a pump 39. The pressure in the chamber 32 and hence in a vessel 42 is a measure of the movement of the beam and, therefore of the propeller torque, and this pressure is measured by a mercury manometer 41. The measuring medium may be air instead of liquid.