Reversing switch for motor vehicle transmission

A reversing or direction-selector switch for a transmission of a motor vehicle having an electro-hydraulically controlled transmission unit which can be switched over from forward to reverse drive by the switch. According to the invention, a switch lever has a one-piece construction with at least a pair of cams for actuation of sensitive switches (microswitches) and forms a pivot body from which the lever arm of the switch lever is mounted and also is provided with a guide for receiving an indexing means, for example, a ball detent for releasably positioning the lever in one of the selected positions thereof.

FIELD OF THE INVENTION 
Our present invention relates to an electrical switch for an 
electro-hydraulic motor vehicle transmission and, more particularly, a 
direction-selector switch for a transmission of the latter type which has 
a switch lever displaceable between forward-drive and reverse-drive 
positions. 
BACKGROUND OF THE INVENTION 
Electro-hydraulic transmissions can be provided with switching devices 
forming selector switches capable of selecting the direction and speed or 
transmission ratio of the drive. In British Pat. No. 1,327,040, for 
example, a switch is described which comprises a switch lever pivotally 
mounted in a housing for actuation of sensitive switches or microswitches 
which perform the direction-selection actuation. 
This switch arrangement is somewhat complex, being composed of parts which 
must be attached by screws and which differ from one another so that they 
do not involve the use of interchangeable parts. 
Assembly of the device is complex and, as a result, manufacture, assembly 
and use are somewhat complicated. 
Other switch arrangement may be provided as well but here too the number of 
switch contacts and switching combinations which must be provided 
complicates the set-up of the switch, especially if it is intended for 
reversing applications, for example switch-over from forward to reverse 
drive or vice versa. 
OBJECTS OF THE INVENTION 
It is, therefore, the principal object of the present invention to provide 
a switch of the direction-selector type for an electro-hydraulic 
transmission for a motor vehicle which obviates the disadvantages of 
earlier switch devices. 
Still another object of the invention is to provide a reversing switch for 
a machine of the aforedescribed type having components which are simple to 
construct and thus can be economically produced. 
SUMMARY OF THE INVENTION 
These objects and others which will become apparent hereinafter are 
attained, in accordance with the present invention, in a reversing switch 
for a motor vehicle electro-hydraulic transmission which comprises a 
housing provided with at least two electrical switch elements and a switch 
lever pivotally mounted in this housing for actuating the electrical 
switch elements. 
According to the invention, the lever, which comprises a lever arm 
projecting from the housing and actuatable by the hand of the user, and a 
lever body within the housing forming the pivot axis for the lever, is 
unitarily composed of, for example, a molded synthetic resin and thus is 
of a one-piece construction consisting of the arm, the lever body forming 
the pivot by which the lever is swingably mounted in the housing, cams on 
the body for actuating the switch elements and a guide for a detent or 
indexing means, for example a spring-loaded ball, adapted to cooperate 
with means on the housing for indexing the lever in its selected 
positions. 
Thus the lever arm is automatically, by being formed in one piece 
therewith, rigid with the cams, the pivot-forming portions and the guide 
for the indexing means. 
When the lever is formed unitarily by molding it in one piece from a 
synthetic resin material, a reinforcement may be provided therein which 
can extend into this lever body as well as into the arm. 
The one-piece construction of the switch lever enables simple mounting of 
the latter within the housing and facilitates fabrication of the 
individual parts as well as assembly of those components used with the 
lever, for example the indexing spring, indexing ball, and like elements. 
According to a feature of the invention, surrounding the arm is a further 
spring, hereinafter referred to as a pressure spring, which bears axially 
outwardly in a direction opposite the direction in which the indexing 
spring urges the ball, against a sliding sheet (shutter) which rides on an 
arcuate surface formed by the interior of the housing and thus blocks the 
slot in the housing through which the arm projects. 
According to a feature of the invention, the body is formed with a pair of 
oppositely extending pins which define the pivot axis of the body and 
which are aligned along this pivot axis which, of course, can be 
perpendicular to the axis of the arm. 
Preferably the body is a flat member from which the pins extend in opposite 
directions to be received in tubular bosses molded on a pair of identical 
housing portions which are attached together in mirror symmetrical 
relationship so that their bosses receive the pins. 
Since the housing portions can be formed as molded shells and can be 
identical, obviously the fabrication of the housing is a simple matter. 
The two shell portions can define the aforementioned slot which is closed 
by a sealing shutter formed as the sliding sheet. 
According to yet another feature of the invention, the two housing shells 
opposite this slot are formed with a plurality of indentations cooperating 
with the ball which constitutes the index member in the guide of the 
switch lever body. This ball can be urged by a synthetic resin disk 
outwardly, the disk forming a seat for the indexing spring. 
The sliding sheet forming the shutter can be composed of metal and thus can 
be biased by its inherent resiliency in a slidable manner against the 
curved surfaces of the housing shelves thereby closing the slot in a 
dust-tight manner. 
Each half shell can, moreover, be formed with slits which are traversed by 
the flexible band of a pipe clamp enabling the housing to be mounted upon 
a column. 
It has been found to be advantageous to provide the halfshelf so that 
symmetrical with their longitudinal axis, the housing is formed with 
projections from one shelf half reaching toward the other and recesses on 
the opposite shelf half and such that the projections and recesses 
interfit to form junctions. 
The reinforcement extending through the arm of the lever can be a wire and 
we have also found it to be advantageous to provide the cam means as a 
pair of cam formations to each side of a longitudinal median plane through 
the switch lever which can actuate respective pairs of switch elements.

SPECIFIC DESCRIPTION 
FIGS. 1 through 3 of the drawing illustrate an embodiment of the invention 
in which the switch lever has three positions in which it can be indexed, 
namely, a neutral position N, a forward position V and a reverse position 
R. In the embodiment of FIGS. 4 and 5, however, a total of five positions 
can be provided, namely, two forward positions V.I and V.II which can 
represent first and second forward speeds, the neutral position N and two 
reverse drive positions RI and RII also representing two reverse speeds. 
While not particularly relevant to the specifics of the switch with which 
the present invention is primarily concerned, it should be noted that the 
switch can be utilized with any machine having an electrohydraulic 
transmission between, for example, a prime mover such as an internal 
combustion engine, and a load such as the driven wheels of a motor 
vehicle. 
Typically the sensitive switches, frequently referred to as microswitches 
herein, are connected in electrical circuits with solenoid valves and the 
battery or another power source of the vehicle to control the hydraulic 
pressurization of hydraulic brakes or clutches which, in turn, can 
selectively immobilize certain elements of planetary gear transmissions or 
interconnect elements of planetary gear transmissions to other such 
elements or to various shafts to effect speed selection or direction 
selection. 
The term "speed selection" is used to refer to the ratio interposed between 
the input and output shafts of the transmission, either in terms of speed 
or in terms of torque and the expression is thus equivalent to an 
expression such as "transmission ratio selection." 
However, the term "direction selection" is used herein to indicate 
selection of either the forward or the reverse direction and, when the 
lever is used to select one direction or the other and does not also 
select a speed or speed range, some other control conventional in the art, 
may be required to provide ratio selection as described. 
In FIGS. 1 through 3 we have shown a direction selector switch for a 
transmission of the type described which comprises a housing 1 having an 
upper and lower molded half shells 2 and 3 which can be identical but 
which are positioned in substantially mirror-symmetrical relationship as 
shown in FIG. 2 with the symmetry plane coinciding with a median plane 
through the housing and perpendicular to the plane of the paper in FIGS. 2 
and 3. The housing 1 is affixed by a pipe clamp 4 to a column which has 
been represented only diagrammatically at 4a in FIG. 3, the pipe clamp 
comprising a strap 4b adapted to encircle the column and passing into the 
housing through a slot defined at 1a between the two housing parts and 
merging from the housing through a similar slot, the opposite ends of the 
strap being tightened together by rotation of the hex-head 4c of a screw 
4d traversing the lugs 4e and 4f of the strap and threaded into a nut 4g 
engaging the lug 4f. 
The two housing portions 2 and 3 are molded with registering bores 6, 7, 8, 
9 at four corners of a rectangle and which can be traversed by screws 
which connect the two housing portions together. At an end of the housing 
remote from the column, the two housing portions define a slot 10 between 
them, this slot being formed in an arcuate wall 29 which is also defined 
by the two housing portions, the slot being covered by a sliding sheet 
(shutter) 11 of metal which rests, as a result of its inherent resiliency, 
along the arcuate surface 29 and moves with a switch lever generally 
referred to at 5. 
In the solid line position shown in FIG. 1, this lever is in its neutral 
position. The lever comprises a lever arm 40 which is molded unitarily 
with a body 35 from synthetic resin material, the arm being reinforced by 
a metal rod or wire as shown at 41 in FIG. 2 and having a hand grip 49 
which can be screwed or simply slid on the free end of this arm. 
Before the grip 49 is mounted, a coil spring 28 is slipped over the arm 40 
and seated against the body 35 at the junction of the arm 40 therewith, 
this spring forming a pressure spring which biases a pressure disk 30 
against an O-ring 27 forming a seal between the O-ring 27, the arm 40 and 
the sheet 11 and urging the sheet 11 against the surface 29. Thus the 
sheet 11 moves the am 40 and closes the slot 10 in a dust-tight manner. 
The opposite ends of the slot 10 limit the angular stroke of the switch 
lever 5 so that, in the extreme positions thereof, the lever can occupy 
either the dot-dash position V, corresponding to forward speed, or the 
dot-dash position R, corresponding to reverse speed. 
The body 35 is formed unitarily with a pair of lateral flanges or 
projections 12, 13, symmetrically of opposite sides of a median plane 
along the axis of the arm 40 and perpendicular to the plane of the paper 
in FIG. 1. 
Members 12 and 13 are contact cams which operate the actuating pins 14 and 
15 of a pair of sensitive switches (microswitches) mounted in the housing 
by having lugs 33 of these switches anchored in correspondingly shaped 
recesses in the housing walls of the housing 1. 
Pins 31 which can be molded or fitted into the base portions of the shell 
halves 2 and 3, can fit into tubular rivets of these sensitive switches to 
retain the latter in position against the forces applied by the cams 12 
and 13 when the lever 5 is respectively swung in the clockwise and 
counterclockwise senses from the neutral position shown in solid lines in 
FIG. 1. 
The body 35 is also formed unitarily with a pair of oppositely projecting 
but axially aligned pins 18 and 19 of cylindrical configuration, these 
pins extending perpendicular to the median plane of the housing and being 
received respectively in tubular bosses 2a, 3a in the housing portions 2 
and 3 respectively. These bosses are provided, as can be seen in FIG. 3, 
with blind bores 36 and 37 respectively. Thus, the unitary or one-piece 
structure of the switch lever 5 includes not only the arm 40 and the body 
35 but also the cams 12 and 13 and the pins 18 and 19 which pivotally 
support the lever in the housing. 
The body 35 is formed with another blind hole (FIG. 3) shown at 20 and 
forming a guide for a detent or indexing ball 23. 
A coil spring (indexing spring) 21 is received in the bore 20 and bears 
against a setting disk 42 which is slidable in this bore and urges the 
ball 23 outwardly. 
The ball 23 is engageable selectively in one of three arcuate recesses 24, 
25 and 26 (in the neutral, forward and reverse positions) in the housing 1 
to index the switch lever. The lever is thus held in its selected position 
until sufficient force is applied to overcome the force of the spring 21 
and allow the ball 23 to jump into the next recess. 
Both half shells 2 and 3 are formed on their confronting faces when they 
are in the position shown in FIGS. 2 and 3, projections 28 on one side and 
recesses 38 adapted to receive the projections, the projections and 
recesses 38, 39 centering the shells with respect to one another and 
enabling them to be interfitted. 
FIG. 2 shows the two half shells 2 and 3 with the switch lever 5 disposed 
between them such that the pins 18 and 19 project into the blind bores of 
the two half shells. 
From FIG. 3 it can be seen that the rear wall of the housing defined by the 
half shells forms the recesses or indentations 24, 25, 26 in which the 
ball can be engaged and hence the relationship of the indexing means with 
the housing. From this FIGURE as well as the strap of the pipe clamp 
running through slots 42 and 43 can be seen. 
The half shell 3 can be formed with a bore in which a grommet 45 is 
anchored to retain the leads connected to the switches. 
In the embodiment of FIGS. 4 and 5 additional recesses are provided for the 
indexing ball and, in this embodiment, the body or hub portion 135 of the 
switch lever 105 has two segments 106, 107, each of which has a pair of 
cams 112, 113 and 112A, 113A disposed in different planes (see FIG. 5) for 
actuating respective pins 114 of stacked switches 116, 116A and 117, 117A 
on each side of the housing. On changing to the additional forward or 
reverse speeds, the additional switches are thus operated by the added 
cams. 
The remaining parts of the housing and other structure similar to that 
described in connection with FIGS. 1 through 3 have been designated by 
similar reference numerals preceded by a hundreds digit.