In the service and repair of marine engines, it is desirable to remove the propellor from the propellor shaft without damaging the shaft and, consequently, avoiding the considerable expense associated with the replacement of a propellor shaft. Ordinarily, the propellor shaft is splined and a propellor hub or sleeve is slotted for frictional engagement with the propellor shaft. In some instances, the propellor blade and hub will have a key-way type slot and be tapered for a tight frictional fit; other arrangements utilize a pin that extends through both the propellor shaft and propellor hub. Separation of the propellor shaft and hub in the prior art require external forces applied in opposite directions to the propellor shaft and propellor blades. The propellor blades extend radially from the propellor sleeve and after a period of use in a marine environment, the sleeve becomes tightly locked to the propellor shaft; unbalanced forces tend to bind the hub and shaft and thus aggravate the lock. Expeditious removal of the propellor, therefore, without severe damage to the propellor shaft or components of the engine requires a puller device that applies uniform forces that promote removal while avoiding a binding lock.
There are various types of blade configurations and arrangements for a propellor. Most marine propellers have two or three blades. It would, therefore, be desirable to provide a propellor puller device that can accommodate these various blade numbers, configurations and arrangements. The prior art discloses tension transmitting chain links or flexible chains that engage each of the propellor blades where the chains utilize a hook member that hooks to the propellor blade such that when the chain link is placed in sufficient tension, the propellor is urged from its lock with the propellor shaft. In order to place the chain links in tension and achieve sufficient tension to separate the propellor puller, devices were used that caused rotation to occur in the centering recess of the propellor shaft while transmitting a compression force to the propellor shaft. The compression, however, distorted the centering recess in the end of the propellor shaft and consequently interfered with a uniform force distribution. The prior art discloses devices that utilize a threaded axle that threadably engages a nut member such that rotation of the threaded axle results in a compressive force being applied to the end of the propellor shaft. The conical recess located in the center of the propellor shaft at its end centers the compressive force such that it acts axially along the propellor shaft; rotation of the threaded axle transmits the compressive force through the conical recess and results in the recess becoming distorted. Thus, it is desirable to provide a propellor puller device that permits the compressive force to be transmitted through the recess to the propellor shaft by rotation of the threaded axle member without distorting the centering recess on the propellor shaft.
It is also desirable that the tension forces acting through the chain links are provided uniformly to break the friction lock between the hub of the propellor blades and the splines on the propellor shaft.
It is an object of the present invention to provide a propellor puller device that uniformly distributes the tension forces acting on the propellor hub to separate it from the propellor shaft and to permit compressive engagement with the centering recess of the propellor shaft without distortion of the recess.
USPTO Backgrounds
USPTO Backgrounds