192 clutches and power-stop control – Clutches – Plural clutch-assemblage
Reexamination Certificate
1999-10-27
2001-03-20
Lorence, Richard M. (Department: 3611)
192 clutches and power-stop control
Clutches
Plural clutch-assemblage
C192S083000, C074S335000, C074S473110
Reexamination Certificate
active
06202812
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a shift actuator for moving a transfer case between high, low and neutral positions which is simplified when compared to the prior art.
Transfer cases are utilized in many medium to heavy vehicles to allow shifting between high and low ranges, and also movement into a neutral range. The transfer case typically allows rotational drive from a vehicle engine to be distributed between front and rear axles. The shift actuator allows changing the rotational drive between high and low ranges. The provision of the neutral position allows the operator to place the vehicle into neutral while still driving a power take-off. The power take-off on medium to heavy vehicles is often used to power auxiliary functions. Examples of such auxiliary functions are driving a winch, a boom for utility trucks, etc.
One challenge in providing three distinct positions is to have the shift actuator movable, and securely held at each of the three positions. Typically, cylinders are utilized to drive a shift fork between the particular positions. In one known arrangement, a valve rod moves with the shift actuator. The valve rod has two pneumatic pistons which selectively drive the rod between two positions. One piston is selectively engaged with a surface on the rod to contact and drive the rod to the third position. Typically, the known devices have required part of unique and complex configurations.
It would be desirable to provide a simplified shift actuator for vehicle transfer cases.
SUMMARY OF THE INVENTION
In a disclosed embodiment of this invention, a shift rod for moving a shift fork extends between two ends. Pneumatic cylinders are disposed adjacent each end for selectively driving the rod between the three positions. A spring drives the rod to a first position. If the two cylinders are vented to atmosphere, the spring is the sole driving force on the rod, and maintains the rod in a first position. A second position is achieved by applying pneumatic pressure through a first pneumatic cylinder in opposition to the spring. This holds the shift rod at the second position. The first and second positions are preferably the high and low positions, respectively. The shift rod has an end which moves through a spacer toward a second pneumatic cylinder. The second cylinder includes a separate piston. The separate piston is operable to move upon pneumatic pressure being delivered into the second hydraulic cylinder. The piston contacts an end of the rod, driving the rod in opposition to pressure in the first cylinder. Since the pressure in the second cylinder is assisted by the spring force, the rod moves in the direction of the pressure of the second cylinder, and the spring force against the first cylinder pressure. This causes the rod to move back away from the second position. The second cylinder is preferably provided with a spacer or stop which stops movement of the second piston after a predetermined amount of movement. At that location, the second piston is maintained against the stop, and abutting an end of the rod. The rod is thus held at an intermediate position, which is preferably neutral in the transfer case. The present invention thus utilizes only simple pneumatic structure, and reduces the complexity of providing a reliable shift actuator for vehicle transfer cases.
These and other features of the present invention can be best understood from the following specification and drawing, the following of which is a brief description.
REFERENCES:
patent: 2092580 (1937-09-01), Kelley
patent: 2802554 (1957-08-01), Pringle
patent: 4261216 (1981-04-01), Braun
patent: 4702127 (1987-10-01), Cote
patent: 5020419 (1991-06-01), Amedei et al.
patent: 5669265 (1997-09-01), Adler
patent: 6076420 (2000-06-01), Ito et al.
Carlson & Gaskey & Olds
Lorence Richard M.
Meritor Heavy Vehicle
LandOfFree
Simplified transfer case shift actuator does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Simplified transfer case shift actuator, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Simplified transfer case shift actuator will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2499498