Abstract: An improved linear guiding mechanism with a standing part and a moving part which have respective uniform cross sections. A pair of spaced guiding channels is formed between these parts and respective linear ball bearings are arranged in both channels that interconnect the two parts. The channel walls are abutting the balls via steel bars extending along the channels. Preferably the standing part defines a cylinder in which a piston is moved and its shaft is connected to the moving part. The parts are made of light and soft material such as aluminum or plastic and manufactured by extrusion technique. The rather high variation of dimensions of such parts are compensated by means of biasing forces that press the channels together, and the biasing forces are sufficiently high to resist operational load. The length of the ball bearings is at least the half of the maximum stroke.

Abstract: The invention relates to a toy which has an annular frame with a curved, osed interior surface. A small toy vehicle is movable by manually moving and orienting the frame, for rolling on wheels around the curved interior surface. A retaining tether attaches the toy vehicle to the frame to permit the wheels to leave the interior surface of the frame but not to separate it entirely from it. In the preferred embodiment a continuous channel is provided throughout the entire interior of the frame and a slit communicates between the interior channel and the exposed interior surface of the frame. One end of the tether is tied to the toy vehicle and the other end is tied to a bead retained within the channel and freely moving throughout the entire length.

Abstract: The invention realizes fluent drive without dead points by continuously cging the angle between the levers (13,14) of the pedals (1). The two pedal levers (13,14) are fixed to two separate shafts (15,16) with common axis (3). The driving shaft (18) is eccentric to this axis (3) and the mechanical connection between the driving shaft (18) and the shafts (15,16) of the pedal levers (13,14) is realized by eccentrics (19,20). With this construction the pedals move faster when coming upwards and slower when going downwards, so when the depressed pedal reaches its lowest point, the other one has already passed its highest point.

Abstract: The invention relates to a new process for dewatering the sludges arising from the aerobic and/or anaerobic decomposition of e.g. household sewages, by treating with chemical agents, which comprises adjusting the pH of the sludge to a value between 9 and 12 by adding at least one of a compound selected from the group consisting of calcium and magnesium hydroxide and calcium and magnesium oxide, then mixing 50 to 5000 g./m.sup.3, of formaldehyde and/or dimethylolurea to the sludge suitably in the form of an aqueous solution, then optionally adding a dusty or granular substance capable of adsorbing oils and fats in an amount of 0.5 to 15% by weight as calculated for the dry substance content of the sludge, and adding prior to the adjustment of the pH or after the optional treatment with said substance capable of adsorption to the sludge 20 to 500 g./m.sup.3.