referring now to the drawings wherein the showings are for the purpose of illustrating the preferred embodiments of the invention only , and not for the purpose of limiting same , in fig1 a spring unit illustrated has a housing 1 with two longitudinal side walls which are connected in the form of a u via an end wall , and at their end regions directed away from the end wall , are angled obliquely outwards and are provided with inwardly directed flanges 2 which extend in a plane perpendicular with respect to the longitudinal side walls and which each have an opening 3 , which is oval in the example illustrated and is intended for receiving pins 4 , which are only illustrated in fig7 . the end wall of the housing has a central opening through which there projects one end of a cylinder 5 &# 39 ; of a hydraulic impact damper 5 designed as a piston / cylinder unit , said end being provided with crosswise slits . a flange 6 is integrally formed on the cylinder of the impact damper 5 and supports the cylinder 5 &# 39 ; of the impact damper 5 axially on the inside of the housing end wall . the flange 6 is adjoined , on the cylinder 5 &# 39 ; of the impact damper 5 , by an external thread , on which there is arranged a spring abutment 7 which can be screw - adjusted axially in the manner of a nut . in the example illustrated , this spring abutment is formed by a plate - like part which is guided axially , by way of shoulders 7 &# 39 ; ( see fig1 ), on longitudinal side borders of the longitudinal walls of the housing 1 and is thus retained in a non - rotatable manner relative to the housing 1 . the piston rod 5 &# 34 ; of the impact damper 5 retains a further spring abutment 8 , which resembles a stay . a helical compression spring 9 , which is concentric with the impact damper 5 , is clamped in between spring abutments 7 and 8 . this helical compression spring 9 stresses the spring abutment 8 against a t - shaped end , as seen in the view of fig3 of a tilting lever 10 , which is provided with two hook - like lateral continuations 10 &# 39 ; ( see fig3 ) which , when the tilting lever 10 assumes its normal position , according to fig1 to 5 , grip around the pins 4 on their side which is directed towards the spring abutment 8 . the tilting lever 10 is accommodated in an end - side slit 11 of the stay - like spring abutment 8 , i . e ., the spring abutment 8 overlaps the top side of the tilting lever 10 , which can be seen in fig1 by way of a continuation 8 &# 39 ; and overlaps the underside of said tilting lever , which can be seen in fig5 by way of a continuation 8 &# 34 ;. these continuations 8 &# 39 ; and 8 &# 34 ; are , for their part , provided with mutually aligned longitudinal slits 12 , which are open only on their sides which are directed towards one another , or directed towards the tilting lever 10 , and at their ends which are oriented in the direction of the free end of the tilting lever 10 . the longitudinal slits 12 accommodate a bolt 13 , which passes through a corresponding opening in the tilting lever 10 , between the continuations 10 &# 39 ; of the latter . this bolt 13 forms a hinge - like articulated connection between the spring abutment 8 and the tilting lever 10 , with the articulation axis parallel to the pins 4 . the arrangement illustrated in fig1 to 6 functions as described hereinafter . the helical compression spring 9 , which is supported on the end wall of the housing 1 via the spring abutment 8 and the flange 6 and the cylinder 5 &# 39 ; of the impact damper 5 , stresses the spring abutment 8 against the bolt 13 and thus forces the tilting lever 10 into engagement with the pins 4 by way of its hook - like continuations 10 &# 39 ;. the spring stressing of the helical compression spring 9 can be changed by screw - adjustment of the spring abutment 7 on the cylinder 5 &# 39 ; of the impact damper 5 . for this purpose , the cylinder 5 &# 39 ; of the impact damper 5 is turned appropriately by virtue of a tool engaging in the crosswise slits at that end of the cylinder 5 &# 39 ; which projects out of the end wall of the housing 1 . if the tilting lever 10 is subjected to a lateral force or a torque which results in the tilting lever 10 pivoting around one of the pins 4 , then the spring abutment 8 is displaced in the direction of the spring abutment 7 , counter to the force of the helical compression spring 9 and counter to the resistance of the impact damper 5 , which acts in parallel with said spring 9 . in this case , the more abruptly , i . e ., the more quickly , the pivot movement of the tilting lever 10 takes place , the more effective is the resistance of the impact damper 5 . this means that pronounced dynamic force peaks are predominantly absorbed by the impact damper , while the helical compression spring 9 produces a resistance irrespective of the pivot speed of the tilting lever 10 and also produces a restoring force . according to fig7 the housing 1 may be fixed on a ski 14 , for example by means of the pins 4 , such that the impact damper 5 and the helical compression spring 9 are aligned approximately parallel to the longitudinal direction of the ski . the tilting lever 10 may bear a boot - retaining means 15 , which encloses one end of a ski - boot sole in the central position from above and from the sides and releases the boot when the latter is subjected to a disruptive force which forces the boot sideways to a sufficient extent , the tilting lever 10 and the boot - retaining means 15 being pivoted in the process . the design of the impact damper 5 is explained hereinbelow with reference to fig7 . the cylinder 5 &# 39 ; has a stepped axial bore 16 passing through it and , as seen in fig7 the left - hand end of said bore has a small diameter and the right - hand end region , which adjoins a central region of larger diameter , of said bore is provided with an internal thread . the left - hand region of the axial bore 16 with the smaller diameter accommodates one end of the piston rod 5 &# 34 ; in a displaceable manner , the other end of said piston rod passing through a central bore of a base part 17 which is screwed into the threaded section of the axial bore 16 . in the central section of the axial bore 16 , the piston 18 of the piston rod 5 &# 34 ; separates two chambers 16 &# 39 ; and 16 &# 34 ;, which communicate with one another via a throttle gap which remains between the outer circumference of the piston 18 and the inner circumference of the central section of the bore 16 . these two chambers 16 &# 39 ; and 16 &# 34 ; are sealed with respect to the outside by the gap between the left - hand end of the piston rod 5 &# 34 ; and that part of the axial bore 16 which guides said end of the piston rod 5 &# 34 ; being sealed by two sealing rings 19 , which are arranged , with the capacity for a certain amount of axial displacement , in an annular groove of the above - mentioned part of the piston rod 5 &# 34 ;. the annular gap between the central bore of the base part 17 and that part of the piston rod 5 &# 34 ; which passes through said bore is blocked off by a sealing ring 20 , the central bore of the base part being provided , on its side of the base part which is directed towards the piston 18 , with an annular - step - like widening for the purpose of accommodating said sealing ring 20 . the sealing ring 20 is secured axially in this widening by an annular disc 21 , which is clamped in axially between the base part 17 and the annular step between the threaded section and the central section of the axial bore 16 of the cylinder 5 &# 39 ;. in addition , the gap between the base part 17 and the axial bore 16 can be blocked off by a sealing ring 22 , which is accommodated in an annular - step - like depression on the outer border of the outer end side of the base part 17 and rests against a smooth section of the inner circumference of the axial bore 16 , said smooth section axially adjoining the threaded section of this axial bore 16 . in order to secure the sealing ring 22 axially , protrusions which grip around the sealing ring 22 in a hook - like manner may be provided on the outer end side of the base part 17 . the chambers 16 &# 39 ; and 16 &# 34 ; are filled with a hydraulic medium , which is of a pasty consistency , that is , has a high viscosity in the rest state , but nevertheless can flow well when subjected to force . media of this type have no tendency to creep through seals in the rest state . this is important because the contact - pressure force of the sealing rings 19 , 20 and 22 remains comparatively low when the impact damper 5 is at a standstill and because skis , for example , are used only over a short period of time in the year , and accordingly , movement of the impact damper 5 is infrequent . since the impact damper 5 is designed as a synchronous unit , i . e ., the piston rod 5 &# 34 ; has the same cross - section on both sides of the piston 18 , the overall volume of the chambers 16 &# 39 ; and 16 &# 34 ; remains constant as the piston 18 is displaced . accordingly , the provision of a separate chamber for receiving displaced hydraulic medium is rendered superfluous , i . e ., is not necessary . insofar as pronounced temperature changes result in an unequal change in the volume of the hydraulic medium and the volume of the chambers 16 &# 39 ; and 16 &# 34 ;, the compliance of the sealing rings 19 , 20 and 22 , in particular of the sealing rings 19 , provides sufficient compensation . the coupling between the piston 5 &# 34 ; and the spring abutment 8 may be designed releasably in the manner which can be seen in fig3 and 4 . that end of the piston rod 5 &# 34 ; which is directed towards the spring abutment 7 has an annular groove , into which a spring ring 23 can be clamped . the spring abutment 8 has an end - side recess 24 of u - shaped cross - section and a lateral and end - side opening . a slit 25 is arranged in the wall of the recess 24 , and the spring ring 23 can be pushed into said slit , transversely with respect to the longitudinal axis of the piston rod 5 &# 34 ;, when the piston rod 5 &# 34 ; is pushed into the recess 24 , with lateral displacement . the invention has been described in detail with particular emphasis on the preferred embodiment , and variations and modifications within the spirit and scope of the invention may occur to those skilled in the art to which the invention pertains .
the invention relates to a boot - retaining unit of a ski binding or snowboard binding , having a boot - retaining element which is retained compliantly by virtue of a spring mechanism , and having a hydraulic impact damper which is arranged parallel to the spring mechanism and is in the form of a piston / cylinder unit . according to the invention , the impact damper contains a hydraulic medium of high viscosity in the rest state and has virtually no tendency to flow , and accordingly , cannot escape at the impact - damper seals even in the course of long rest periods . the cylinder of the impact damper is preferably provided with an external thread and is provided as an adjustment screw for the purpose of changing the spring stressing .