GB739739A - Improvements in or relating to shimmy damper - Google Patents

Abstract

739,739. Aircraft undercarriages. HOUDAILLE-HERSHEY CORPORATION. Sept. 16, 1953 [Feb. 11, 1953], No. 25601/53. Class 4. [Also in Group XXXII] A shimmy damper installation for an aircraft undercarriage wherein the wheel assembly is subjected to damping over a limited range only of its castering movement and is disconnected from the damping mechanism over the remaining portion of its movement comprises a strut 14 non-rotatably attached to the aircraft and associated with a relatively movable cylinder 13 to which the wheel-mounting fork is attached. The strut 14 carries two freely rotatable collars 40, 41 the collar 40 being connected to the wheel-carrying fork by a scissors linkage 46 and the collar 41 having an integral arm 48 connected by a link 49 to a further arm 31 clamped to the spindle 30 of a rotary piston or vane type hydraulic damping assembly 15 secured to the strut 14. The arm 31 has a cranked extension 35 having an upwardly extending portion 35b which is engaged on opposite sides by the free ends of a coiled centering spring 36 surrounding the assembly 15, the free ends being in contact also with opposite faces of a fixed bar 25 secured to the mounting of the assembly 15. The collar 41 carries, offset from its centre, a spring-loaded plunger 55 adapted to register with a recess 57 in the collar 40 whereby the two collars may be connected to transmit castering movements of the wheel to the damper assembly 15. Such damping is required over a limited range only of the full castering movement and to enable the wheel to caster freely beyond such movement the plunger 55 is formed with a laterally projecting head having cam faces on its under surface adapted to engage with opposed cam faces 63 on members fast with the strut 14 to withdraw the pin 55 from the recess 57 and to allow it to rest on the upper face of the collar 40. The spring 36 restores the wheel and collar 41 to its mid-position after castering and the pin 55 engages automatically with the recess to re-render the damping mechanism operative. The assembly 15 may be used for steering the undercarriage.