Metal working – Method of mechanical manufacture – Impeller making
Reexamination Certificate
1998-07-10
2001-02-13
Hughes, S. Thomas (Department: 3726)
Metal working
Method of mechanical manufacture
Impeller making
C029S270000, C029S259000, C029S426500, C029S256000
Reexamination Certificate
active
06185817
ABSTRACT:
FIELD OF THE INVENTION
The present invention is generally related to propellers adapted to engage a shear pin disposed through a propeller shaft, and more particularly to a tool adapted to assist in removing the propeller from the propeller shaft when the shear pin becomes damaged or broken.
BACKGROUND OF THE INVENTION
There are many types of propellers adapted for use with watercraft motors. Each propeller is designed to be suitable for an intended use, such as for high speed, high torque, use in a weedy environment and so forth. From a mechanical standpoint, the propeller is secured to a drive shaft for rotation therewith. To prevent damage to the motor and drive shaft should the propeller engage an obstruction or fixed object, the drive shaft is typically provided with a shear pin which is disposed through a bore defined radially through the drive shaft. The propeller is adapted about the drive shaft and engages the shear pin such that the propeller is rotatably driven by the extensions of the shear pin. Should the propeller engage a fixed structure or obstruction, such as a rock, tree limb, stump or the bottom of a lake, the shear pin is mechanically constructed to deform or break, thereby momentarily or permanently disengaging the propeller from the drive shaft to avoid damaging the engine or drive shaft. Thus, the propeller will cease to rotate, either temporarily or permanently, due to the deforming or breaking of the shear pin. In essence, the shear pin is the safety mechanism or “circuit breaker” that prevents damage to the engine and drive shaft driving the propeller.
When the shear pin becomes damaged or broken, replacement of the pin is necessary. If the shear pin becomes damaged or bent, typically the propeller will vibrate and generate excessive vibration and noise which is noticeable to the operator and renders the operation of the propeller inefficient. Removing and replacing the shear pin is cumbersome and difficult for the operator. Often, it is difficult to remove the propeller from the drive shaft due to the location of the propeller with respect to the boat and the operator, and, due to the fact that the propeller often becomes jammed against the drive shaft due to the damage of the shear pin. Often times, a boat operator will attempt to remove the jammed propeller to gain access to the shear pin by using conventional tools, such as screwdriver, to leverage the propeller from the drive shaft. Often times, this leveraging damages and renders totally useless the propeller since the propeller is often comprised of plastic and can become cracked. One conventional prior art propeller implementing a shear pin is described in U.S. Pat. No. 4,482,298 which discloses a weedless propeller, the teachings of which are incorporated herein by reference. One embodiment of this propeller is shown in
FIGS. 1-3
of the present application. This propeller is widely used throughout the industry. Unfortunately, this propeller is prone to damage if not removed properly, as it is typically comprised of plastic and cracks when the operator attempts to remove the propeller to gain access to the damaged shear pin.
The present invention sets forth a tool to facilitate effectively removing a propeller from the corresponding drive shaft when the shear pin becomes broken or damaged.
SUMMARY OF THE INVENTION
The present invention achieves technical advantages as a tool for effectively removing a propeller blade from a drive shaft when a shear pin becomes damaged or broken. The tool of the present invention has a mechanism for engaging the blades of the propeller to prevent rotation of the blades with respect to the tool. An advancement member is disposed through an axis of the tool and is adapted to leverage against the distal end of the drive shaft as a leverage point. By advancing the advancement member against the drive shaft, the tool effectively removes the propeller from the drive shaft to expose the damaged shear pin without damaging the propeller.
According to the preferred embodiment of the present invention, the tool comprises a body member having a central axis. A securing mechanism is coupled to the body member and is adapted to engage the blades of the propeller and also to prevent the rotation of the propeller with respect to the body member. An advancement mechanism is disposed proximate the body member central axis and is adapted to leverage against the propeller shaft to thereby cause the securing mechanism to remove the propeller from the drive shaft. Preferably, the body member has a major surface having a configuration adapted to lie juxtaposed to the propeller face. The securing mechanism preferably comprises a plurality of fingers extending substantially perpendicular from the body member major surface. Preferably, the fingers each extend from an edge of the body member and are spaced equidistant from the each other. The fingers each have a distal end preferably are shaped to adapt securely against the respective blade of the propeller when disposed about the propeller. Preferably, the distal ends are cupped. In the preferred embodiment, the advancement mechanism preferably comprises an adjustment member extending along a central axis of the body member and is axially adjustable therealong to adjust a spacing between the body member and the drive shaft. The body member preferably has a threaded hole. The adjustment member comprises a threaded member threadably disposed within the body member threaded hole. The threaded member has a handle adapted to be grasped by a human hand for rotating the threaded member. In each of the various embodiments, the tool preferably has the same number of fingers as the number of blades of the propeller the tool is adapted to be engaged against, but this is not required.
A method of the present invention uses the tool of the present invention to remove the propeller from the drive shaft. The method comprises disposing the tool about the propeller such that the securing mechanism engages the propeller blades and restricts the rotation of the body member with respect to the propeller. Thereafter, the advancement mechanism is advanced against the propeller shaft to cause the tool to remove the propeller from the propeller shaft. The cupped ends of the fingers grasp the backside of the propeller blades to pull the propeller shaft off and away from the distal end of the drive shaft without damaging the propeller.
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Lorentz Ordie G.
Sims Billy R.
Blount Steve
Duel Products, Inc.
Hughes S. Thomas
Navarro Arthur I.
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