GB430337A - Improvements in and relating to shock-absorbers - Google Patents

Abstract

430,337. Pneumatic shock-absorbers. LANGGUTH, W., 61, Rue Corot, Ville-d'Avray, Seine-et-Oise, France. Nov. 13, 1933, No. 31634. Convention date, Nov. 12, 1932. [Class 108 (iii)] In a pneumatic shockabsorber having a plurality of chambers, at a given value of the pressure in the primary chamber due to movement of a piston therein, the primary chamber is placed in communication with a secondary chamber of equal pressure so that on increase of pressure in the primary chamber the pressure curve of the primary chamber deviates in such a manner that the tangent to the new portion of the curve at the point of deviation is nearer the horizontal than the tangent to the old portion of the curve at the same point. In the operation of the construction shown in Fig. 1, when the piston k reaches the position X the pressure in the primary chamber a, which is substantially equal to that in the secondary chamber b, lifts the spring-pressed valve v so that further movement of the piston compresses the air in both chambers, the rate of increase of pressure being less than that occurring during movement of the piston to position X. On the return movement shock is prevented by a rubber pad g or by a cushion of compressed air formed during the forward stroke of the piston by the passage of air through small piston-perforations h. The valve v may be replaced by a flap-valve controlled by air or spring pressure or by a rod projecting from the piston. In the construction shown in Fig. 2, the rod m of a slide-valve connected to the hollow piston k, is slotted at its lower end and in the position shown its upper end closes two sets of apertures f, q, in secondary chambers b, c. When the piston reaches the position X the pressures of the air in the chambers a, b are substantially equal and when the slots z uncover the apertures f further movement of the piston compresses the air in both chambers. When the piston reaches the position Y the pressure in the chamber c is substantially equal to that in the chambers a, b and after the slots z uncover the apertures q, the piston compresses the air in all three chambers. In a modification, the chamber a is first put into communication with the chamber b and afterwards the chamber b into communication with the chamber c. In another construction the hollow piston k, Fig. 3, has apertures i in its upper and lower surfaces so that when the piston enters the chamber a the air therein is compressed due to the volume taken up by the piston-rod u. When the lower surface of the piston reaches the position O it uncovers apertures f in the secondary chamber b and further movement of the piston compresses the air in both chambers. In a modification of the construction shown in Fig. 1, the secondary chamber b is connected to the primary chamber a by a flexible pipe, and the spring pressing the valve v is replaced by compressed air. A number of such shock-absorbers for use, for example, on an aeroplane, may be connected by flexible pipes to a common secondary chamber, in which case the rate of increase of pressure for a single shock-absorber is less than the rate of the shock absorbers acting together. Each shock-absorber may have its own secondary chamber and these chambers may all be in communication or may communicate in groups. The drawings include a diagram showing the variation in the rate of increase in pressure with movement of the pistons in the constructions described. The Specification as open to inspection under Sect. 91 comprises also other constructions. In Fig. 4 (Cancelled), the secondary chamber b is formed inside the hollow pistonrod u by means of a movable partition u<1>, and the piston k is apertured for the passage of a slide valve rod m fixed to the cylinder. When the piston reaches the position X its lower edge uncovers orifices z in the rod m and the chambers a, b are placed in communication. Fig. 5 (Cancelled), shows a second piston k<1> separating the chambers a, b so that when the pressures in the two chambers are equal further increase in pressure moves the piston kl. In a modification the chambers a, b are formed in telescoping cylinders. This subject-matter does not appear in the Specification as accepted.