Machine element or mechanism – Control lever and linkage systems – Multiple controlled elements
Reexamination Certificate
2001-05-09
2002-11-26
Bucci, David A. (Department: 3682)
Machine element or mechanism
Control lever and linkage systems
Multiple controlled elements
C192S083000
Reexamination Certificate
active
06484600
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a pneumatic three-position shift mechanism for use in vehicle transfer cases wherein the number of components to provide the shift mechanism is reduced compared to the prior art.
Vehicle transfer cases are typically provided with the ability to move a shift yoke between a first position at which is engages a low speed gear, a second position at which it engages a high speed gear, and a third intermediate neutral position at which neither gear is engaged. Typically, these systems have incorporated a shift rod that is movable within a two-part housing between the three positions. At one end of the shift rod are a pair of cylinders movable within three different chambers and between the several positions. At the opposed end of the shift rod is a guiding chamber in which the shift rod is movable.
In the prior art, all of the fluid chambers are provided by separate housings which are bolted to the main transfer case housings. With each separate housing, the number of seals and fluid tight connections that must be utilized increases. Thus, with the prior art, there are required seals and securing devices for separate fluid housings at each of the two ends of the transfer case.
FIG. 1
shows an example
20
of the prior art transfer case. A housing
22
has a split line
24
dividing two housings sub-portions
26
and
28
. A shift rod
30
is received extending between the two, and moves a shift collar
32
to selectively engage one of the two gears
34
and
36
. Gear
34
is a low speed and gear
36
is a high speed gear. The collar
32
is shown in the intermediate or neutral position.
A fluid cylinder
38
is bolted to one end of the housing
28
. The other housing portion
26
receives the bolted on fluid housing
40
. Housing
40
receives the rear end
42
of the shift rod
30
and housing
38
receives the forward end
44
which moves with a plurality of pistons to achieve the various positions of the collar
32
.
As can be appreciated, with the separate housings
38
and
40
a good deal of additional attachments, seals, etc. are necessary.
SUMMARY OF THE INVENTION
In the disclosed embodiment of this invention, the chambers for receiving both the piston and preferably the remote end of the shift rod are formed by integral bores in the transfer case housings. In this way, the bores are self-sealed, and no separate sealing elements or elaborate fluid-type securing devices are necessary.
In a preferred embodiment of this invention, both of the chambers are formed by bores. The bore for receiving a remote end is preferably a blind bore extending into the housing. The bore for receiving the piston end of the shift rod is preferably a bore which opens outwardly through a plurality of stepped bore portions. One of the pistons is preferably of a larger diameter and is movable within a first stepped portion. An end cap is received with a second outer diameter stepped portion of the bore, and provides the outer end for the fluid cylinder. This cap is all that need be secured to the housing in a fluid tight manner. As can be appreciated, the present invention thus greatly reduces the number of required components.
These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description.
REFERENCES:
patent: 4920813 (1990-05-01), Willford
patent: 5012725 (1991-05-01), Leary
patent: 5067323 (1991-11-01), Bennett et al.
patent: 5125326 (1992-06-01), Sarcona
patent: 6202812 (2001-03-01), Semke
Bennett John L.
Larsen Herbert A.
Bucci David A.
Carlson & Gaskey & Olds
Hansen Colby
Meritor Heavy Vehicle Technology LLC
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