Abstract: Improvement in wheelchair lifts generally of the dual hydraulic parallelogram type employing a lever arm assembly which assists in the rotation of the platform from the stowed position to the horizontal deployed position, by providing a gas spring disposed in the lever arm assembly connected at an outboard end to the lifting mechanism link and at an inboard end to at least one of the A arm, the B arm or the common pivot pin of the lever arm assembly. The outward force of the gas spring causes the sliding shoe of the lever arm assembly to maintain contact with the outer face of the lower link of the lifting parallelogram so that upon deployment of the lift during the gravity down phase from stowed position to horizontal transfer position, the inboard end of the platform is pulled up so that it rotates smoothly and is not subjected to free fall.

Abstract: A grinding wheel is disclosed with a disk-like, cylindrical shape, whose perimeter is equipped with a grinding abrasive and has at least one spiral groove. The groove extends essentially around the perimeter at an acute bevel angle of inclination less than 45.degree. to a radius line normal to the axis of wheel rotation. Preferably the bevel angle is designed as an acute angle and is sized so that the groove extends over at least one full circumference of the grinding wheel. The face of the ribs may be tapered and the corners chamfered. Multiple parallel or non-parallel grooves may be employed. Improved cutting, service life and surface characteristics of the processed workpiece are obtained.