Abstract: A roller skate in which the automatic action of normal walking produces a driving action on the wheels. A heel kick to the pedal of the skate causes the putting in operative position of a control device. During the lifting of the skate, the control device comes back to a standby position. A toe kick to the pedal after the waiting position causes the putting in braking position of the control device. The braking is controlled by the depression of the pedal and is progressive. The control device is locked in the position selected and a new position requires the reversion to the standby position.

Abstract: A tractor hitch in which a pair of lower implement attachment links (10) are stabilized by a pair of sway blocks (16) with rubbing surfaces (16a) which cooperate with the links or rubbing blocks (30) on the links to control the amount of sidesway of the links. Each sway block (16) is mounted adjacent its upper end on the tractor by a mounting device (17,18,19,20,21,24) which allows the block to pivot generally in a transverse plane relative to the tractor and adjustment devices (25,26,27,27',28) are provided at the lower end of each sway block to allow the angle of pivot of the block to be continuously adjusted to set the amount of permitted side sway of the links when the links contact the lower ends of the blocks. The spacing (X) between the rubbing surfaces (16a) at the upper ends of the sway block (16) is also adjustable and shock cushioning (31) may be included in the mounting device of the sway blocks to cushion the links against sideways loading arising from loads carried by the links.