GB1237372A - Improvements in or relating to means for mounting engines on test benches - Google Patents

Abstract

1,237,372. Engine test beds. JOHN CURRAN Ltd. Aug. 5, 1968 [June 9, 1967] No. 26626/67. Heading G1W. A bed supporting a gas turbine jet engine Fig. 9 under test comprises stationary and movable supports 25, 29 and connections 31, 32 acting there between comprising flexible link elements 10a, 10b, Fig.3 (not shown) arranged so that, at least under certain test conditions, one link 10a is in tension and the other 10b in compression, the latter being provided with a relatively stiff length 14 located between two relatively flexible lengths to confine the region of flexing. Both links may be stiffened, Fig. 4, they may be staggered and the common part 13 may be on the stationary or movable part. Each support connection may comprise two thin metallic straps 54, 55 Fig. 10, with their opposite ends clamped between spacer blocks 56, 57 by bolts 58 securing them to lugs 51, 52 and a frame 50 to which the engine carrier 40 is secured. The central parts of the straps 54, 55 are clamped between pairs of rigid plates 59, which are apertured to receive a sleeve 60. The ends of the sleeve 60 are connected to spigots engaged in apertures in bearing plates 61, 62 (relative to which the sleeve can be adjusted) and the plates 61, 62 are carried by a stationary base 66 frame through trunnions 64, 65. Engine thrust is measured by a load cell 68 positioned between a member 67 (secured to the frame 50 through the spacers 56, 57 and lugs 51, 52) and an anvil 69 carried by a rigid yoke 70 attached to the base 66. The lengths of each strap 54, 55 between the central spacers 59 and outer spacers 56, 57 are surrounded by stiffening plates 72, 73 connected thereto non-positively by bolts 75 arranged to connect the plates 72, 73 at points beyond the edges of the straps, the grip being insufficient to transmit tensile or compressive loading from the straps to the plates. Protective end covers may also serve as stops to limit movement should a strap break. The strap may be of 16 gauge steel sheet approximately 0À064 inches thick and of total length 30 inches, and the unit may accomodate a deflection under thrust of up to 0À02 inches or even 0À1 inches. Vertical and transverse thrusts can also be measured in apparatus with further supports mounted one on another by similar strap units for limited relative movements in the required directions. Other methods of stiffening flexible elements are envisaged and rigid links if flexibility is provided at the ends e.g. with coiled springs, leaf springs or elastomeric brushes arranged to distort angularly in shear.