Marine propulsion – Screw propeller – Having transmission
Reexamination Certificate
1999-05-20
2001-04-17
Morano, S. Joseph (Department: 3617)
Marine propulsion
Screw propeller
Having transmission
Reexamination Certificate
active
06217400
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a control for a marine transmission and more particularly to an improved actuator assembly for such transmissions.
Conventional marine transmissions employ a driveshaft which has a bevel gear that is affixed to its lower end and which is engaged with a pair of diametrically opposed, and hence, counter-rotating-driven beveled gears. This driven bevel gears are journaled on the propeller shaft and are selectively clutched for driving relationship therewith by a dog-clutching mechanism that is positioned between the bevel gears.
It is conventional to utilize a shift plunger which extends into one end of the propeller shaft and which operates in conjunction with a pin that carries the dogclutching element for effecting the axial shifting of the dog-clutching element into engagement with selected ones of the driven counter-rotating bevel gears.
Various types of mechanisms have been employed for actuating the shift plunger. Some of these utilize a cam mechanism that is operated by a rotating cam formed at the lower end of a shift rod which is actuated by the vessel operator. This cam mechanism requires the cam to be held against rotation about the propeller shaft axis while the shift plunger does rotate along with the pin that couples it to the dog-clutching element. Hence, a number of small pieces must be assembled together in order to complete this mechanism. This adds to the cost and complexity and also gives an area where failures may occur.
Another type of mechanism employs a crank pin that operates in a slot in the shift plunger. This eliminates the need for the connecting member to permit relative rotation. However, these types of mechanisms require a fairly large bearing area and generally make it difficult to keep a small size for the lower unit. If the lower unit's size is increased, particularly at its forward end where this mechanism resides, then hydrodynamic drag can be unacceptably increased.
It is, therefore, a principal object of this invention to provide an improved transmission control for a marine transmission reversing-gear shifting mechanism.
It is a further object of this invention to provide an improved actuating mechanism for the shift plunger of a marine transmission that can be relatively small in operation and size, can be conveniently assembled, and also will have a relatively large bearing area.
SUMMARY OF THE INVENTION
This invention is adapted to be embodied in a marine transmission that is comprised of a propeller shaft having a pair of counter-rotating-driven bevel gears journaled on its forward end. A dog-clutching element is disposed in keyed relationship with the propeller shaft between these driven bevel gears. The dog clutching element is axially movable therealong to effect driving engagement between selected ones of the driven bevel gears and the propeller shaft. A shift plunger extends within a bore formed in this end of the propeller shaft and is coupled to the dog-clutching element for effecting its reciprocation into driving engagement with the selected driven bevel gear.
An area at the upper portion of the lower unit is formed with a key hole shaped opening through which a shift rod passes. The shift rod has a cylindrical bearing portion that is complementary in diameter to the cylindrical portion of the key hole shaped opening, and thus is rotatably journaled therein. A crank arm depends from this bearing portion and is engaged in a groove formed in the shift plunger for operating the shift plunger upon rotation of the shift rod. The crank arm has an offset dimension which is only slightly less than the long dimension of the key hole shaped slot, so that it can pass through the key hole shaped slot for assembly purposes.
REFERENCES:
patent: 4302196 (1981-11-01), Blanchard
patent: 4530667 (1985-07-01), McCormick
patent: 4689027 (1987-08-01), Harada et al.
patent: 4861295 (1989-08-01), McElroy, Jr. et al.
patent: 5151059 (1992-09-01), Higby
patent: 5575698 (1996-11-01), Ogino
patent: 1-119499 (1989-05-01), None
Beutler Ernest A.
Morano S. Joseph
Sanshin Kogyo Kabushiki Kaisha
Wright Andrew
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