Abstract: A double-acting piston and cylinder assembly has a piston which in turn has an outer piston surface centered on an axis, a radially outwardly open piston groove and a pair of axially oppositely facing piston ends. The cylinder has an inner surface centered on the axis and spaced radially outside the outer piston surface. A tubularly annular element received in the piston groove has an outer surface centered on the axis and bearing radially outwardly on the cylinder so the piston is guided in the cylinder by the outer element surface.

Abstract: A seal and guide assembly has an outer normally fixed element having a cylindrical throughgoing passage centered on an axis, extending between an axially inside high-pressure side and an axially outside low-pressure side, and having an inner element surface formed with a shoulder facing the inside high-pressure side. A cylindrical normally axially slidable element extends axially between the sides through the passage and has an outer element surface spaced radially inwardly of the inner element surface.

Abstract: The invention provides a universal hydraulic press for injection-moulding where two separate clamping units, each with a respective mould, are arranged in parallel and are adapted to be brought into alternate engagement with each of two injection units in which a different moulding material may be housed. One of the moulding materials may be injected into one of the moulds following which indexing movement brings the other injection unit into register with that mould for injecting the second material onto the first.

Abstract: A seal mountable between a piston-like element and a cylinder-like element, one of which is formed with a groove opening toward the other, has a supple annular core with an inner periphery and an outer periphery spaced radially therefrom. One of these peripheries lies in the base of the groove and the other periphery is turned radially toward the other element. A central contact ring is compressed radially between the other periphery and the other element and at least one rigid guide sleeve has an end region at least partially surrounding the core and formed with an end face axially engageable with the contact ring. The sleeve lies between the elements. The annular core is elastomeric, the contact ring is formed of readily deformable material having a very low coefficient of friction, and the guide sleeve is formed of a very stiff and durable synthetic resin.

Abstract: A scraper-type shaft seal comprises an outer C-section ring which is received in an inwardly open groove in a housing and which itself receives the outer periphery of an inner ring formed with a lip which engages the outer surface of a shaft to be sealed. One of the rings is formed of flexible hard material and the other of the rings is relatively supple so that the lip of the inner ring can readily follow lateral deflections of the shaft. The outer surface of the outer ring is generally frustoconical so that when fit into a cylindrical groove the lip is prestressed inwardly.

Abstract: A seal engageable with the outer surface of a shaft and fittable within an inwardly open groove formed in a housing between a high-pressure zone and a low-pressure zone has a cup packing integrally bonded to a supple pressure-distributing ring. The packing is of asymmetrical section and is formed with a radially extending flange and with a lip extending from one axial side of the flange toward the high-pressure zone with the inner face of the lip lying resiliently against the outer surface of the shaft. The pressure-distributing ring has an end surface bonded to the one side of the flange, an inner periphery formed with a recess snugly receiving and bonded to the outer face of the lip, and an outer periphery resiliently engaging the interior of the housing groove. A nonresilient antiextrusion ring is received in the packing at the other axial side of the packing.