Note: Descriptions are shown in the official language in which they were submitted.
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DESCRIPTION
CONTROL MECHANISM FOR APPLYING A BRAXE AND
NEUTRALIZING A TRANSMISSION OF A VEHICLE
Technical Field
This invention relates to a control
mechanism for operating a transmission and applying a
brake of a vehicle, and more particularly to a control
mechanism for simultaneously applying the brake and
assuring that a transmission actuating member is in a
neutral position.
Back~round Art
The control mechanism disclosed in U.S.
Patent No. ~,5~1,497 to C. W. Riediger, et al on
; September 17, 1985, and which was specifically
constructed for steering and operating the
transmission of a track-type vehicle, has been
extremely well received by the industry. In such
mechanism, a tiller arm extends outwardly from an
upstanding member which is rotatable about a fixed
axis, and the vehicle is steered as the tiller arm is
swung in either direction away from a generally
i 25 centered neutral position. In order to change at
least one of the speed range of the vehicle and the
direction of longitudinal movement of the vehicle, a
handgrip portion is supported on the tiller arm for
rotation about its own axis. Thus, the handgrip
portion can be conveniently grasped by an operator's
downwardly facing left-hand palm as the vehicle is
traveling forwardly it can be steered to the left by
swinging the tiller arm forwardly. Simultaneously,
the vehicle can be shifted from a forward to a reverse
~ 35 speed by merely twisting the handgrip portion about
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its own axis throuyh a relatively limited angular
range.
A mechanically separated speed selector
lever has heretofore been used with the aforementioned
steerable tiller arm and its twistable handgrip
portion. This requires the operator to release the
tiller arm and grasp the juxtaposed speed selector
lever in order to make a speed range shift of tha
vehicle transmission. Upon completing the range
shift, the speed selector lever is released and the
left hand returned to the tiller arm. This is not
only fatiguing and vexatious, but can delay the
operator's attention from other tasks. Normally, the
operator's right hand is used extensively for
manipulating an implement control lever, and as the
operator's left hand passes between the separated
control members, there is a slight delay in using the
right hand.
In addition, the separated speed selector
lever has heretofore been automatically forced back to
a neutral position when a separate parking brake lever
has been moved to a BRAKE-ON position. Consequently,
when the parking brake lever is subsequently released
it is positively assured that the vehicle is in
neutral and not in an operating gear. Although the
parking hrake lever was inconvenient to reach and a
relatively complex mechanical connection was used
between the parking brake lever and the speed selector
lever, it is a desirable feature.
Thus, what is desired is a simplified and
reliable control mechanism for operating a vehicle
that includes a swingable tiller arm for steering
purposes, a transmission actuating member supported on
the tiller arm for controllably changing one of the
longitudinal direction of movement of the vehicle and
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the speed range of the vehicle, and a brake device
compatibly associated with the swingable tiller arm
and the transmission actuating member. Specifically,
the brake device should include a brake actuating
member so constructed and arranged as to fully take
into account the principles of economy of motion of a
single hand as it is moved between a BRAKE-OFF
position and a BRAKE-ON position. Simultaneously, the
brake device should interact with the transmission
actuating member and assure the neutralization of the
transmission of the vehicle when the brake actuating
member is moved to the BRAKE-ON position.
The present invention is directed to
overcoming one or more of the problems as set forth
above.
Disclosure_of the Invention
In one aspect of the invention, a control
mechanism is provided for applying a brake and
operating a transmission of a vehicle having an
element mounted on the vehicle for limited rotational
movement about an upstanding axis and which includes a
first actuator device for controlling the transmission
and movement of the vehicle including a transmission
actuating member mounted on the element and being
limitedly rotatable about a second axis between a
plurality of operating positions and a NEUTRAL
position, and a brake and neutralizer device for
simultaneously restricting movement of the vehicle and
urging the transmission actuating member to the
NEUTRAL position and including a brake actuating
; member mounted on the element and being limitedly
rotatable about a third axis between a BRAKE-OFF
position and a BRAKE-ON position, and cam means for
positioning the transmission actuating member to the
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neutral position in response to movement of the brake
actuating member to the BRARE-ON POSITION, the cam
means being directly mechanically connected to the
brake actuating member.
In another aspect of the invention, a
control mechanism ~or operating and braking a v2hicle
includes a housing assembly mounted fox swinging
movement about an up tanding ~irst axis, a
transmission actuating member mounted on the housing
assembly for rotation about a second axis betwsen a
plurality of transmission operating positions and a
NEUTRAL position, a brake actuating member mounted vn
the housing assembly for limited rotary movement about
a third axis substantially parallel with the second
axis between a BR~KE-OFF position and a BRAKE-ON
position, and coupling means ~or solely mechanically
interconnecting the brake actuating member and the
transmission actuating member and rotationally moving
the transmission actuating member to the NEUTRAL
position in direct response to the manual movement o~
the brake actuating member to the BRAKE-ON position.
More particularly, a tiller arm extends
outwardly of a housing assembly that is rotatable
about an upstanding axis, and the vehicle is ste red
;~ 25 as the tiller arm is swung in either direction from
neutral. A directional actuating member and a speed
actuating member are mount~d adjacent one anothex on
the tiller arm for limited rotation about a second
axis, such that the operator's downwardly facing hand
palm can conveniently grasp either of the actuating
: members to change the direction or speed range of the
vehicle while simultaneously steering the vehicle. A
parking brake actuating lever is secured to the upper
portion of the swingable housing assembly and when it
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is moved to a BRAKE-ON mode, a neutralizing member
operates to automatically urge the directional
actuating member from either of the FORWARD or REVERSE
positions to a centrally located NEUTRAL position in
the event that the directional actuating member was
inadvertently left in one of such positions. This
feature prevents movement of the vehicle with the
vehicle parking brake engaged, and upon the subsequent
release of the parking brake actuating member to the
BRAKE-OFF position assures that the transmission is
not in an active driving condition. Furthermore, the
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control mechanism employs simple and effective
push-pull control members for the individual operation
of four hydraulic control valves.
Other aspects and advantages of the present
invention will become readily apparent upon reference
to the accompanying drawings and the following
description.
Brief Description of the Drawings
Fig. 1 i5 a diagrammatic, rear elevational
view of the control mechanism of the present invention
with portions of the housing walls broken away and
certain elements illustrated in cross section to
better show details of construction thereof;
Fig. 2 is a fragmentary, diagrammatic, top
plan view of the control mechanism illustrated in Fig.
1 including portions of a tractor's operating station
and various control members in the vicinity of the
tractor seat;
Fig. 3 is a fragmentary, diagrammatic, cross
sectional view as taken along line III-III of Fig. 1;
Fig. 4 is an enlarged, fragmentary,
diagrammatic, cross sectional view as taken along line
IV-IV of Fig. 1;
Fig. 5 is a fragmentary, diagrammatic, cross
sectional view of the housing supporting structure
shown in Fig. 1, only as taken from the left side
thereof;
Fig. 6 is a diagrammatic view of the
neutralizing member shown in Fig. 4 in an elevated
BRAKE-OFF condition in solid lines and in a lowered
BRAKE-ON condition in phantom lines; and
Fig. 7 is a block diagram plan view of the
power train of the vehicle with four hydraulic control
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valves associated therewith which are operated by the
control mechanism of Fig. 1.
Best Mode for Carrying out the Invention
Referring to Fig. 2, a transmission,
steering, and parking brake control mechanism 10
constructed in accordance with the present invention
is illustrated in conjunction with an operator station
12 of a track-type vehicle identified generally by the
reference number 14. The operator station includes a
tractor seat 16 having left and right arm rests 18 and
20, an implement control lever 22, and an auxiliary
control lever 24. The control lever 22, for e~ample,
is of the joy-stick type for ad~usting the elevation
and tilt angle of a bulldozer blade mounted on the
vehicle. The auxiliary control lever 24 is typically
used for operating a ripper or a winch mounted on the
tractor. The location and operation of such
implements are well known in the art although they are
not shown in the drawings. The control levers 22 and
24 are manipulated by the operator's right hand, while
the control mechanism 10 is manipulated by the
operator's left hand.
As is illustrated in Fig. 7, the vehicle 14
also includes an engine or power plant 11 drivingly
connected to a power shift transmission 13 having a
~plurality of forward speeds and a plurality of reverse
speeds. The longitudinally oriented transmission
powers a cross drive mechanism 15 oriented
transversely of the vehicle, which has left and right
output members 17 and 19. The output members
powerably rotate left and right drive wheels or
sprockets 21 and 23, and left and right parking brakes
25 and 27 are operatively connected therewith to
inhibit the rotation of the individual drive wheels.
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As is shown in Fig. 1, the control mechanism
10 includes: a) a steering selector apparatus 26 for
steering the vehicle 14 by rotating an elevationally
lower output lever arm 28 about a fixed upstanding
axis 30; b) a first actuator device 32 for controlling
the direction of longitudinal movement of the vehicle
by the generally vertical displacement of a first
push-pull control or cable assembly 34; c) a second
actuator device 36 for controlling the speed range of
the vehicle by the generally vertical displacement of
a second push-pull control or cable assembly 38; and
d) a brake and transmission neutralizer device 40 for
simultaneously restricting movement of the vehicle by
the generally vertical displacement of a third
push-pull control or rod assembly 42 and for urging
the first actuator device 32 to a neutral position by
the swinging movement of a profiled neutralizing
member 44.
The steering selector apparatus 26 includes
a steering selector spool 29 which is adapted to be
proportionately axially displaced in a first hydraulic
control valve 31 to the counterclockwise turn or
clockwise turn positions. As can be generally
appreciated by reference to Fig. 7, the first
hydraulic control valve 31 controls the flow of
hydraulic fluid between an engine driven steering pump
45 and a reversible steering motor 47 selectively
driving the cross drive mechanism 15. For example,
; the counterclockwise rotation of the vehicle about its
30 ~ own central vertical axis results in a left turn when
trauelin~ forwardly.
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The first actuator device 32 includes a
directional selector spool 33 which is adapted to be
; axially displaced in a second hydraulic control valve
35 to either a FORW~RD position or a REVERSE position
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at the opposite sides of a centralized NEUTRAL
position as is shown in Figs. 1 and 7. And, the
second actuator device 36 includes a speed selector
spool 37 which is axially displaced in a third
hydraulic control ~alve 39 to obtain a preselected one
of a plurality of speed range positions such as FIRST
GEAR, SECOND GEAR and T~IRD GEAR.
The brake and neutralizer device 40 includes
a parking brake selector spool 41 which can be axially
displaced in a fourth hydraulic control valve 43
between a BRAXE-OFF position and a BRAKE-ON position.
More particularly, the steering selector
apparatus 26 includes a tubular tiller arm 46 defining
a central outstanding axis 48 which preferably extends
upwardly at a slight angle from a hori~ontal plane as
is identified by the letter D in Fig. 1. As is shown
in Fig. 2, the central axis 48 extends generally
toward the fixed upstanding axis 30 in a slightly
offset manner, and when the vehicle 14 is travelling
in a straight longitudinal direction, the axis 48 is
preferably at a preselected angle B forwardly of a
transverse vertical plane thought the axis 30.
The tubular tiller arm 46 includes a distal
end flange 50 and an outer cylindrical surface 52
concentrically arranged along the central axis 48, and
is rigidly secured to a supporting pedestal element 54
intermediate the ends thereof. In turn, the pedestal
element is releasably secured to a swingable housing
assembly 56 by a plurality of threaded fasteners or
bolts 58, one of which is illustrated. As is shown in
Fig.s 1 and 5, the housing assembly 56 has an upper
profiled case 60, an intermediate tubular portion 62,
an intermediate adapter portion 64, and a lower
tubular portion 66 arranged along the upstanding axis
30 and releasably secured together by a plurality of
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elongate threaded fasteners or bolts 68. A stationary
fr'ame 70 has an upper deck 72 and a lower deck 74, and
upper and lower bearing support structures 76 and 78
are provided for mounting the housing assembly 56 for
swinging movement about the upright axis 30. The
upper bearing support structure 76 includes a ball
bearing assembly 80 entrapped between the upper
profiled case 60 and the intermediate tubular member
62, and is generally held stationary by an annular
retaining member or collar 82 releasably connected to
the upper deck 72 as by a plurality of threaded
fasteners or bolts. 84. The lower bearing support
structure 78 is optional, although it is preferred,
and in the instant example includes another ball
bearing assembly 86 contained within a retaining ring
device 88. The retaining ring device 88 is releasably
secured to the lower deck 74 as by the threaded
fasteners or bolt and nut assemblies 90, and is used
to stabilizingly center the lower tubular portion 66
of the housing assembly.
The lower part of the intermediate tubular
member 62 defines a central bore 92 on the upstanding
axis 30, and a pair of somewhat larger~diameter
stepped bores 94 and 96 arranged along a diagonally
opposite pair of upstanding axes 98 and 100
respectively radially o~fset the same distance from
the central axis 30. The adapter portion 64 has a
corresponding central bore 102, and a pair of bores
104 and 106 also arranged along the respective axes 98
and lO0.
Turning now to the first actuator device 32,
it may be noted to include a tubular directional
actuating member or first handgrip portion 108
rotatably supported directly by the tiller arm 46.
Preferably, the outer cylindrical surface 52 of the
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tiller arm is hardened and/or coated with a material
having a relatively low coefficient of friction to
more effectively support the directional actuating
member 108. An outer seal ring 109 is located between
the directional actuation member and the tiller arm 46
adjacent the distal end flange 50. The directional
actuating member has a stepped inner flange 110, and
an inner seal ring 112 is seated thereon and engaged
with the outer face of the pedestal element 54 of the
tiller arm 46.
Furthermore, the first actuator device 32
has an inwardly extending cylindrical projection 122
which is illustrated in Figs. 1 and 3. This
projection is rigidly secured to the inner flange 110
of the directional actuating member 108 at a
preselected radius from the central axis 48 of the
tiller arm 46 and parallel to that axis. A
cylindrical ring 123 is fixedly secured to the
projection 122, although it can be adapted to freely
rotate thereon if desired. The projection extends
through an arcuate or kidney-shaped slot 124 defined
; fully through the pedestal element 5~, and at the
inner end thereof has a ball assembly 126 releasably
secured thereto. The first push~pull cable assembly
34 has at its upper extremity an extendable socket
head 128 which receives the ball assembly. Such ball
and socket coupling arrangements are quickly connected
and disconnected and are widely available. The socket
head is connected to a depending cable 130 which is
contained within a tubular sheath 132 and an outer
protecting wrap 134. The distal end of this cable is
connected to the directional selector spool 33.
Advantageously, a first ball bearing
assembly 136 is provided for guidably supporting and
permitting relative angular movement of the push-pull
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cable assembly 34 within the housing assembly 56 and
about its own offset axis 100 as the housing assembly
is limitedly swung about the central upstanding axis
30. The ball bearing assembly is exteriorly seated in
the stepped bore 96 of the tubular member 62, and
internally seated on the outer protecting wrap 134
such that it guidably centers the protecting wrap and
sheath 132. At least a portion of the protecting wrap
is threaded so that an upper nut ~.38 and a lower nut
140 can be screwthreadably adjusted thereon in an
entrapping relationship with the inner race of the
ball bearing assembly. The outer race thereof is
contained by the adapter portion 64 of the housing
assembly.
The second actuator device 36 includes a
knob-like speed actuating member or second handgrip
portion 142 releasably secured to the distal end of an
elongate cylindrical shaft 144. A pair of needle
bearings or sleeve bearings 146, the outer one of
which is shown, rotatably support the opposite ends of
the shaft within the tubular tiller arm 46. The
proximal end of the shaft has a radius arm 147 with a
ball assembly 148 releasably secured thereto. This
ball assembly is contained within an extendable socket
head 150 connected to the upper end of the second
push-pull cable assembly 38. A depending cable 15~ is
connected to the socket head and is adapted to slide
within a tubular sheath 154 and an outer, externally
threaded protecting wrap 156 in a manner similar to
that described with respect to the push-pull cable
assembly 34. A second ball bearing assembly 158 is
provided for guidably supporting and permitting
relative angular movement of the push-pull cable
assembly 38 within the housing assembly 56 about its
own offset axis 98 as the housing assembly is
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limitedly rotated. But since the first and second
ball bearing assemblies 136 and 158 are preferably
identical, the latter need not be further described.
Attention is now directed to Figs.l and 4
and to the brake and transmission neutralizer device
40 which includes a parking brake actuating member or
lever 160 movable between a rearwardly disposed
BRAKE-OFE position as shown in solid lines and a
forwardly disposed BR~KE-ON position as shown in
phantom lines. The generally U-shaped lever has a
spherical knob 162 at the upper end thereof, and a
cylindrical mounting portion 164 at the lower end
which is mounted for limited rotation about an axis
166 substantially parallel to the axis 48 by a support
structure 167 including a pair of needle bearings or
sleeve bearings 168 seated within the upper profiled
case 60. A tubular sleeve 170 is connected to rotate
with the mounting portion 164 by a spline joint 172,
and has the neutralizing member 44 integrally secured
thereto at one end. At the opposite end a pair of
lever arms or mounting ears 176 extend integrally
therefrom. These ears are connected to an upper
spring seat 178 by a pivot pin 180. A lower spring
seat 182 is connected to the inner portion of the
profiled case 60 by a ball and socket joint identified
generally by the reference number 184, and a coiled
compression spring 186 extends between the two seats.
The pivot pin 180 is located at the upper side of a
plane 188 passing through the ball and socket joint
and the axis 166 when the lever 160 is in the
BRAKE-OFF position, and is located at the lower side
of the plane when the lever is in the BRAKE-ON
position and this provides an over-center spring
- a~tion.
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A lever arm 190 is secured to the mounting
portion 164 of the parking brake actuating lever 160
intermediate the opposite ends thereof. An upper
portion 192 of the brake push-pull rod assembly 42 is
connected to this lever arm through a pivot joint 194.
A lower portion 196 depends through the adapter bore
102 and generally along the axis 30 and since the
upper portion is slightly inclined with respect to the
lower portion, another ball and socket joint 198 is
used to connect them. One or more elastomeric or
plastic guide rings 200 can be used, if desired, to
guide the lower portion 196 within the adapter bore or
within the lower tubular portion 66 for concentricity
with the axis 30. The distal end o~ the lower portion
196 i5 connected to the parking brake selector spool
~1, which can be arranged concentrically along central
axis 30, if desired.
Referring to Figs. 4 and 6, the neutralizing
member 44 of the brake and neutralizer device 40
defines a generally C-shaped cam plate 174 which is
profiled to define an arcuate slot 202 and a pair of
contoured entry ramps 204 and 206 at the opposite
sides of the slot which cooperate with the cylindrical
ring 123 on the projection 122 of the directional
actuating mem~er 108 as will later be explained.
Industrial Applicability
Assuming that the engine 11 is started and
running, the directional actuating member 10~ can be
easily rotated by the operator's downwardly facing
left hand palm. It is an easy motion to rotate it in
a clockwise direction when looking inwardly along the
axis 48 to the FORWARD mode from the NEUTRAL position
of the projection 122 shown in Fig. 3, or in a
counterclockwise direction to the REVERSE mode from
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the NEUTRAL position. The angular movement identified
by the letter C is approximately 35 in each instance.
When the projection is in the FORWARD mode, the ball
and socket joint 126,128 shown in Fig. 1 is elevated
and this raises the cable 30 connected to the
directional selector spool 33 and pulls it outwardly
of the second hydraulic control valve device 35. When
the projection is lowered for the REVERSE mode, the
cable 30 is pushed to retract the directional selector
spool. The lower end of the cable extends through a
curved path to the directional selector spool which
could be at almost any angular orientation.
The speed actuating member 142 is typically
located in FIRST GEAR and may be rotated therefrom in
even increments in a clockwise direction when viewing
inwardly along the axis 48 of Fig. 1 to the SECOND
GEAR and THIRD GEAR positions. With such rotation of
the speed actuating member, the radius arm 147
illustrated in Fig. 4 is moved in a counterclockwise
position. This elevates the cable 152 and pulls the
speed selector spool 37 outwardly of the third
hydraulic control device 39.
During straight longitudinal movement of the
track-type vehicle 14, the tubular tiller arm ~6, and
the housing assembly 56 are positioned in -the NEUTRAL
position identified by the letter l'N'I in Fig. 2. The
NEUTRAL position is located at an angle B o about 15
forward of a transverse vertical plane through the
upstanding axis 30. It it is desired to steer the
vehicle to the left when travelling forwardly, the
tiller arm is urged forwardly or in a counterclockwise
direction about upstanding axis 30. Advantageously,
the vehicle rotates about its own central vertical
axis or changes its steering heading in the same
35~ direction that the tiller arm is swung about the axis
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30. This causes the corresponding angular movement of
the housing assembly 56 on the ball bearing assembly
80 and the output lever arm 28 shown near the bottom
of Fig. 1. The counterclockwise movement of the
output lever arm 28 pulls the steering selector spool
29 outwardly of the first hydraulic control device 31.
The steering motor 47 is then caused to operated in
the desired direction and at the desired rate of speed
such that the right output member 19 of the cross
driva mechanism 15 of Fig. 7 is accelerated and the
left output member 17 is decelerated approximately the
sama amount. The vehicle is subsequently caused to
rotate in a counterclockwise direction about its own
central vertical axis, although not illustrated, and
to turn to the left. Of course, the clockwise
movement of the tiller arm will correspondingly urge
the steering selector spool 29 inwardly to cause
clockwise rotation of the vehicla and a right turn
when traveling forwardly. When the direction of
longitudinal travel of the vehicle is changed to
reverse, the forward displacement of the tiller arm 46
will still cause counterclockwise rotation of the
vehicle about its own central vertical axis. Both the
full counterclockwise and full clockwise vehicle
turning positions, identified raspectively by the
letters "CCW" and "CW" are located at an angle A of
about 25 from the neutral position. As is shown in
Fig. 1, the steering arm axis 48 is inclined upwardly
at an angle D of about 15 for comfort, since the
forearm and wrist are more relaxed thereat than would
be the case with a horizontal steering arm axis.
one of the features of the control mechanism
10 is that both of the push-pull cable assemblies 34
and 38 are guidably centered by the ball bearing
assemblies 136 and 158 at a fixed radius away from the
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central upstanding axis 30. Thus, when the housing
assembly 56 is rotated in either direction away from
NEUTRAL during steering, the cable assemblies 136 and
158 are individually allowed to rotate about their own
axes 100 and 98. Permitting them to freely rotate
relative to the housing assembly automatically
relieves any twisting strains thereon since the lower
ends of the cable assemblies 34 and 38 are positively
connected to the ~rame-supported directional and speed
selector spools 33 and 37 respectively. If these
cable assemblies were not allowed to freely rotate,
there would be a tendency for them to twist and cause
an undesirable increase in resilient torque acting
against the swinging movement of the steering selector
apparatus 26 about its upstanding axis 30.
Referring now to the brake and neutralizer
device 40 shown in Eigs. 1 and 4, the parking brake
actuating lever 160 may be urged forwardly by the
operator's left hand from the solid line BRAKE-OFF
position to the phantom line BRAKE-ON position.
The mounting portion 164, the sleeve 170 and the lever
arm 190 are subsequently rotated in a counterclockwise
direction about the axis 166 when viewing Fig. 4. In
doing this, the pivot pin 180 is moved in an arc about
the axis 166 from a location at the upper side o~ the
plane 188 to the lower side of that plane. The
compression spring 186 is gradually compressed until
the pivot pin passes through the plane, and thereafter
the compression spring expands and positively urges
the lever toward the BRAKE-ON position with a
desirable over-center snap action. The pivot joint
194 and third push-pull rod assembly 42 are urged
downwardly and the parking brake selector spool 41 is
pushed into the fourth hydraulic control valve device
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43 to simultaneously engage the left and right parking
brakes 25 and 27 of the vehicle shown in Fig. 7.
When the parking brake actuating lever 160
is moved to the forward BRAKE-ON position,the profiled
cam plate 174 is also caused to move in a
counterclockwise direction when viewing Figs. 4 and 6.
In the event that the operator had positioned the
directional actuating member 108 in FORWARD wherein
the cylindrical projection 122 and ring 123 are
arcuately disposed in an elevated position, the cam
plate 174 would contact the ring and urge it
downwardly. Specifically, as is shown in Fig. 6, the
inner entry ramp 204 would contact the elevated ring
as indicated in phantom lines by the reference number
123' and forcibly depress it to the solid line
position illustrated. In a similar manner, i~ the
operator had earlier positioned the directional
actuating member 108 in REVERSE, the ring 123 would be
in a lowered position as indicated in phantom lines by
the reference number 123 ". The subsequent
counterclockwise movement of the cam plate 174 would
cause the outer entry ramp 206 to abut the ring and to
urge it upwardly toward its neutral position shown in
solid lines. The arcuate slot allows the cam plate to
avoid contact with the tubular tiller arm 46 until the
desired amount of travel is provided for the third
push-pull rod assembly 42.
In view of the foregoing, it can be
appreciated that the operator's left hand can be
easily positioned over the directional actuating
member 108 and the wrist limitedly rotated in a
clockwise direction when looking inwardly along the
axis 48 to obtain one of the REVERSE, NEUTRAL or
FORWARD modes, or over the juxtaposed speed actuating
member 142 and the wrist twisted to obtain one of the
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FIRST, SECOND or THIRD SPEED modes. In either case,
the operator's left arm may be simultaneously extended
or retracted to rotate the tiller arm 46 and the
housing assembly 56 about the upstanding axis 30 to
steer the vehicle in the desired direction. Moreover,
the operator can conveniently reposition his left hand
from either of these actuating members to the parking
brake actuating levar 160 located at the top left
portion of the housing assembly 56. This is in marked
contrast to one earlier parking brake actuating lever
located inconveniently at the lower front surface of
the left seat console. The parking brake actuating
lever 160 can be positioned forwardly to the BRAKE-ON
mode when he is through the work task, and this
movement will cause the directional actuating member
108 and associated directional selector spool 33 to be
automatically placed into the NEUTRAL mode in the
event that it was inadvertently left in either FORWARD
or REVERSE. This will minimize use of the parking
brakes as service brakes and extend the service life
thereof, and should the parking brake actuating lever
be immediately returned to the BRAKE-OFF mode will
prevent inadvertent movement of the vehicle in a
positive drive mode. In this regard, it should be
Z5 noted that the vehicle 14 has conventional left and
ri~ht ser~ice brakes, not shown, in operational
relationship with the left and right output members 17
and 19 of the cross drive mechanism 15 in a well-known
manner.
; 30 Other aspects, objects and advantages will
become apparent from a study of the specification,
drawings and appended claims.
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