Abstract: The invention relates to a driving wheel for car engines or the like, incorporating a gear wheel, which is intended to cooperate with a cogged belt, and a pulley attached to one side of the gear wheel and arrested to this. The gear wheel molded from a plastic or similar material having a coefficient of thermal expansion higher than steel's coefficient of thermal expansion and by having a helix of steel or another material with a coefficient of thermal expansion similar to or identical with that of steel embedded in the gear of the wheel radially inside the cogs, whereby the helix has such strength and dimension that it determines the thermal expansion properties of the gear rim.

Abstract: The invention relates to a gear wheel consisting of plastic material or a similar material having a coefficient of thermal expansion higher than that of steel. The gear wheel further includes a helix of steel or another material having a coefficient of thermal expansion similar to or identical with that of steel embedded in the gear rim of the wheel radially inside the teeth, whereby the helix has such a strength and dimension that it determines the coefficient of thermal expansion of the gear rim.

Abstract: A first member, such as a clutch release bearing can be releasably connected to a second member, such as a cup spring in a coupling device, in that the member has a cyclindrical portion, which is insertable in a hole in the second member, the hole being surrounded by radially inwardly directed tongues. The portion is provided with radially outwardly directed projections forming a rim and being of a number and a circumferential extension corresponding to the interspaces between the tongues and which can be displayed through these interspaces. Catch fingers are arranged to be inserted between the tongues and the projections respectively after assembly for preventing unintentional disconnection of the connection. The fingers may be removed from the lock position at dismounting.

Abstract: A lubricating system including an annular channel, lubricant inlet and outlet ports communicating with the channel, a sealing ring made of flexible elastic material of U-shaped cross section mounted in the channel, a plurality of spaced apart supply holes in the ring, pressure in the supply port operable to displace the sealing ring to permit fluid communicating between the inlet port and one of the supply holes. The supply holes are arranged so that two holes are not disposed diametrically opposite one another.

Abstract: The invention refers to wheel-shaped objects such a pulley discs, which incorporate a rigid internal hub, a rigid outer circumferential part and a web interconnecting these parts and being of a material which has a higher coefficient of thermal expansion than the hub and the circumferential part.The invention is characterized therein that the web portion in circular cross-section has a zigzag-like design and that through-grooves are made in the web portion, where this connects to the circumferential part, thus that the material of the web portion at cooling can disengage itself from the circumferential part at these grooves thereby to prevent not desired tensile stresses to develop.