Abstract: The present invention provides a speed adjusting transmission mechanism for adjusting the speed of a rotative belt of a tread mill which comprises an adjustment transmission shaft provided movably between an output shaft of a motor and a driven shaft associated with the rotative belt. The movable transmission shaft is held by a vertical plate which is mounted on a pair of vertical guide supports and which is slideable along vertical rail grooves of the guide supports. This support means is simple and durable. The mechanism further includes V-belt carrying pulleys respectively mounted on the output shaft, two opposite ends of the transmission shaft and one end of the driven shaft. The pulleys mounted on the output shaft and on one end of the transmission shaft each comprise two cone-shaped discs one of which is slideable.

Abstract: A pipe wrench which comprises a body carrying a fixed jaw and pivoted to a handle and a L-shaped member having a rack portion movably inserted in the body and a movable jaw extending out of the body, wherein a pinion is disposed in the body to engage with the rack portion and a detent member which restricts the pinion to turn in a single direction. The detent member is of such a construction that also allow the rack portion to move outward and inward swiftly.

Abstract: A wrench suitable for pipe work which includes a handle having two parallel arms, and a body pivotably mounted on the arms by means of a driving gear which passes through two holes provided on the arms, the holes are formed with internal teeth, a rack bar which includes a movable jaw at the forward end thereof and which has a portion slidably received in the body, wherein the driving gear is meshed with the teeth of the rack bar and which has the axis thereof transverse to the handle, when rotating the driving gear, the rack bar moves toward or away from a fixed jaw attached on the body, there are two sector pinions acting as the detent members mounted on the driving gear and operated cooperatively with internal teeth for permitting the uni-directional rotation of the driving gear with respect to the handle.