Abstract: There is disclosed a detachable lock mechanism which can be installed on automotive-type cooling fans having a conventional fan clutch connection between the fan and the fan drive shaft. The lock mechanism functions by providing a positive mechanical lock between the drive shaft and the cooling fan, thereby bypassing the drive clutch and its function. The locking mechanism provides a desirable positive lock to insure maximum fan speed when operating a vehicle in low gears and low forward speeds. The device is of particular value for off-road service of recreational vehicles and the like which are often operated for extended periods in low gears, conducive to overheating. In these applications, the operation of the fan clutch is detrimental to adequate engine cooling and a mechanical locking mechanism thereby serves a useful function in avoiding overheating of these vehicles.

Abstract: A shaft coupled at one end to motive means is externally threaded in spaced proximate relation with the opposite free end thereof. A plurality of keyways supporting a plurality of keys are provided at the free end of the shaft. A propeller mount supporting a marine propeller for rotation therewith is coaxially positioned over the shaft and has an internally threaded axial bore threadedly coupled to the threading of the shaft. A component is coaxially positioned over part of the propeller mount. An annular restraining member is coaxially positioned over the shaft and within an axial bore of the component. A plurality of bores are formed through the restraining member in alignment with bores of the propeller mount. The restraining member is coupled to the propeller mount via a plurality of screws in the bores thereof with a predetermined gap between the restraining member and the propeller mount thereby preventing axial movement of the propeller mount.