Apparatus and method for signalling coincident machine conditions

The disclosure involves an apparatus for detecting coincidence of (a) a vehicle transmission engaged in the power mode and (b) the operator's seat in a "first" position, i.e., a position other than that from which the vehicle is normally driven. Such apparatus has an annunciator, a first circuit providing a first conductive path when the seat is in the first position and a second circuit providing a second conductive path when the transmission is engaged in the power mode, forward or reverse. When, coincidently, the seat is in such position and the transmission is in the power mode, the first and second circuits coact to energize the annunciator and alert the vehicle operator.

FIELD OF THE INVENTION 
This invention relates generally to vehicles and, more particularly, to 
material handling vehicles. 
BACKGROUND OF THE INVENTION 
The term "vehicle" usually conjures up a mental image of a machine, the 
primary purpose of which is to transport goods and/or people from place to 
place. However, there are certain types of vehicles configured. to perform 
a task in a relatively localized area with the vehicle transportation 
capability being rather ancillary to the vehicle's main purpose. 
A vehicle of the latter type is a construction/digging machine known as a 
backhoe. A primary purpose of a backhoe is to excavate and move earth 
rather than to transport goods or people. Such a machine is not unlike a 
farm tractor in general appearance and in the fact that the operator faces 
forward to drive the machine. However, a backhoe differs from such a 
tractor by virtue of the type of implement with which it is equipped. 
At its rear, a backhoe is equipped with a digging implement comprising a 
hydraulically-operated articulated boom to which is attached a digging 
bucket. The boom and bucket are not unlike a human arm (the "boom") and 
hand (the "bucket"). Digging is with the "fingers," i.e., the bucket 
teeth, pointing generally downward. The boom can be swung in an arc to, 
say, deposit earth on a spoil pile after it has been excavated. A backhoe 
may also have a front-mounted loading bucket in which instance the machine 
is referred to as a loader backhoe. 
A common type of backhoe has an operator's seat which, when facing forward, 
gives the operator access to those controls, e.g., steering wheel, 
throttle, brakes and the like, used to transport the machine from place to 
place. When the seat is pivoted to face rearward (about 180.degree. from 
the forward-facing position), the operator has access to the hydraulic 
valve levers used to set the machine outriggers for stability and to 
operate the implement. Backhoes are commonly seen digging trenches for 
pipelines although backhoes can be (and are) used to perform many other 
digging tasks. 
A way of describing a backhoe is that it has two "systems," namely, the 
implement system and the machine transport drive system. Such systems are 
susceptible to simultaneous operation. But since the operator faces in 
different directions, usually about 180.degree. apart, to perform such 
operations, the possibility of such simultaneous operation gives rise to 
certain concerns. 
That is, after the operator has properly positioned the machine using the 
drive system (and while anticipating the digging task to be performed 
later), s/he may inadvertently try to use the implement to dig while 
leaving the controls in the drive or power mode. (It should be noted that 
such an error would not be made by an operator who is even minimally 
attentive.) 
Persons in the field of machine design have recognized somewhat similar 
possibilities with other types of industrial machines. For example, U.S. 
Pat. No. 5,109,945 (Koga) involves a system used on an industrial fork 
lift truck. While such system detects when the truck operator leaves the 
seat, no operator signal is annunciated. And, of course, the Koga system 
is not suitable for use in applications where the operator does not leave 
the seat when performing any of plural tasks. 
An apparatus and method which signals a vehicle operator when, 
coincidently, the vehicle transmission is in the power mode and the seat 
is pivoted away from the controls used to transport the machine would be 
an important advance in the art. 
OBJECTS OF THE INVENTION 
It is an object of the invention to provide an improved apparatus and 
method overcoming some of the problems and shortcomings of the prior art. 
Another object of the invention is to provide an improved apparatus and 
method for signalling when a vehicle transmission is in the power mode 
and, simultaneously, the operator's seat is in a particular position or 
range of positions. 
Yet another object of the invention is to provide an improved apparatus and 
method for providing an audible signal to a vehicle operator upon the 
occurrence of such a condition. 
Still another object of the invention is to provide an improved apparatus 
and method for use with backhoes. How these and other objects are 
accomplished will become more apparent from the following descriptions and 
from the drawing. 
SUMMARY OF THE INVENTION 
The invention is particularly suited for use with backhoes of the type 
described above. In a backhoe, the machine operator's seat is mounted for 
movement between two positions. The first position may be described in 
terms of the second, i.e., the first being that where the seat is pivoted 
away from the second position. And the latter, second position is the seat 
position from which the operator drives the machine. 
As described in greater detail below, the seat is said to be in the first 
position when a seat center axis is anywhere within a circle arc of, e.g., 
330.degree. or so. The seat is said to be in the second position when its 
center axis is anywhere within the remaining "forward-facing" 30.degree. 
or so of the circle. 
The invention involves an apparatus having both electrical and mechanical 
aspects. Such apparatus, for detecting and signalling coincidence of 
transmission power mode and seat first position, includes an annunciator 
for signalling the machine operator that such coincidence exists. 
The apparatus has a first circuit providing a first conductive path when 
the seat is in the first position and a second circuit providing a second 
conductive path when the transmission is in the power mode. When, 
coincidently, the seat is in the first position and the transmission is in 
the power mode, the first and second circuits coact to energize the 
annunciator and signal the operator. 
The first circuit includes a seat switch which "changes state" when the 
seat is moved between the first position and the second position. (The 
phrase "change-of-state," well understood in the electrical arts, means 
changing from an open to a closed position or from a closed to an open 
position. The phrase is apt, irrespective of whether the device under 
discussion is mechanical, electromechanical or solid state in 
configuration.) 
More specifically, in one type of machine, the seat is mounted for pivoting 
circular movement and may be said to have a center axis extending fore and 
aft. The machine may be said to have a reference axis which is stationary 
with respect to the machine frame. The seat is in the first position, 
i.e., away from the machine driving position and at or pivoting toward the 
implement operating position, when the included angle between the center 
axis and the forward-pointing reference axis is greater than a 
predetermined angle, e.g., 15.degree.-20.degree. or so. 
The contacts of a seat switch change state whenever the operator pivots the 
seat between its first and second positions. Such contacts are used in the 
apparatus for alerting the operator if the seat is pivoted away from the 
driving position while the transmission is engaged for forward or reverse 
power. 
The second circuit includes a transmission switch which changes state when 
the operator shifts the transmission between the neutral mode and the 
power mode. In one highly preferred arrangement, the transmission switch 
is embodied as a pressure switch which is open when the transmission is in 
neutral and closes whenever such transmission is shifted into the power 
mode, i.e., forward or reverse. Alternatively, two pressure switches may 
be used, one being closed when the transmission is in forward or reverse, 
respectively. In another highly preferred arrangement, the transmission 
switch is embodied as an operator-manipulated shuttle switch. 
In other aspects of the invention, the apparatus includes an alarm relay, 
the contacts of which are connected between the annunciator and the first 
circuit. The second circuit includes a transmission relay, the contacts of 
which change state when the transmission is shifted between the power mode 
and the neutral mode. 
In one embodiment, the seat switch, connected in the first circuit, is 
closed when the seat is in the first position and the contacts of the 
alarm relay are closed when the transmission is in the power mode. Since 
the seat switch and the contacts of the alarm relay are in series with the 
annunciator, the annunciator is energized when the seat is in the first 
position and the transmission is in the power mode. 
In another embodiment, the second circuit includes an operator-manipulated 
shuttle switch, contacts of which change state when the transmission is 
shifted between the power mode and the neutral mode. The shuttle switch 
energizes the alarm relay when the transmission is in the power mode and, 
since the seat switch and the contacts of the alarm relay are in series 
with the annunciator, the annunciator is energized when the seat is in the 
first position and the transmission is in the power mode. 
Yet other aspects of the invention involve a method for detecting 
coincidence of (a) the transmission in the power mode and (b) the seat in 
the first position. The method includes, in either order or 
simultaneously, the steps of establishing a first conductive path when the 
seat is in the first position and establishing a second conductive path 
when the transmission is in the power mode. Such method also includes the 
step of annunciating a signal when the conductive paths are established 
simultaneously. 
In more detailed aspects, the step establishing a first conductive path 
includes actuating a seat switch and the step establishing a second 
conductive path includes actuating a transmission switch. Preferably, the 
step establishing a second conductive path also includes actuating a 
transmission relay. 
In one preferred version of the method, the seat switch is of the type 
having contacts closed when the seat is in the first position. 
Transmission relay actuating includes closing contacts in series with the 
annunciator and the seat switch. Electrical power thereby flows through 
the seat switch, the closed contacts and the annunciator and the operator 
is alerted that the transmission is in the power mode and the seat is out 
of its second or "machine-driving" position. 
Other aspects of the invention are set forth in the following detailed 
description and in the drawing.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
Before describing the inventive apparatus 10 and method, it will be helpful 
to have a general understanding of a type of machine for which the 
invention is particularly useful. FIG. 1 illustrates a backhoe 11 having 
an engine 13, a transmission 15 (preferably of the torque converter type), 
a steering wheel 17 and an operator's seat 19. At its rear, the backhoe 11 
has a digging implement 21 comprising a hydraulically-operated articulated 
boom 23 to which is attached a digging bucket 25. 
When urged downward and into the earth by the boom 23 and, usually, by a 
hydraulic cylinder at the "wrist 27," the bucket teeth 29 bite into the 
earth and the bucket 25 fills. When the bucket 25 is filled, the boom 23 
is pivoted left or right and the bucket 25 emptied by pivoting it 
counterclockwise (as shown in FIG. 1) about the wrist 27. 
When the seat 19 faces forward as shown in FIGS. 1, 2 and 3, the operator 
31 has access to those controls, e.g., the steering wheel 17, used to 
transport the machine from place to place. When the seat 19 is pivoted to 
face rearward as shown in FIGS. 4 and 5 (about 180.degree. from the 
forward-facing position), the operator 31 has access to the hydraulic 
valve levers 33 used to set the machine outriggers for stability and to 
operate the implement. 
Before describing aspects of the invention, it will also be helpful to 
provide a brief explanation of some of the terminology used in this 
specification. Referring particularly to FIGS. 2, 3 and 5, it is assumed 
that the seat 19 has a horizontal center axis 35. Such axis 35 extends 
fore and aft when the seat 19 is facing directly forward or directly 
rearward. It is also assumed the backhoe 11 has a central longitudinal 
reference axis 37 which is stationary with respect to the backhoe per se. 
By either of the half-circles 39, 41 (one half-circle 39 in solid line, one 
half-circle 41 in dashed line) FIG. 3 illustrates that the seat 19 is 
capable of 180.degree. pivoting movement. On the other hand, a seat 19 may 
be capable of 360.degree. pivoting movement, either (a) a single 
revolution in one direction before being required to be revolved in the 
opposite direction, (b) multiple revolutions only in one direction or (c) 
multiple revolutions in either direction. 
In any of the foregoing instances, when the horizontal seat axis 35 is in 
registry with that portion 43 of the circle which is shaded, the seat 19 
is said to be in the "first seat position 44." When such axis 35 is in 
registry with a non-shaded portion 45 or 47, the seat 19 is said to be in 
the "second seat position 46." 
And there is another way to describe the first seat position, i.e., in 
terms of the second position. That is, the first position is that where 
the seat 19 is pivoted away from the second position. And the latter, 
second position is the seat position from which the operator 31 drives the 
machine. 
Referring now to the circuit of FIG. 6 illustrating the first embodiment of 
the apparatus 10, certain of the apparatus components will be identified. 
The operation of such circuit will then be described. 
The circuit includes a battery 49 or other source of DC power and two 
pressure switches 51, 53 in parallel. The switch 51 or 53 is closed when 
the transmission 15 is in the power mode in the forward or reverse 
direction, respectively. A normally-closed transmission relay 55 includes 
a coil 57 and a contact 59 closed when the coil 57 is de-energized. 
(This specification makes reference to components which are "normally" open 
or "normally" closed. Such normal state is when the component is in the 
quiescent state and not influenced by external "events," e.g., electrical 
energization or the application of oil pressure.) 
The circuit also has a normally-closed alarm relay 61, the contact 63 of 
which is closed when the relay coil 65 is de-energized. The relay contact 
63 is in series with a two-position seat position switch 67 which is 
closed when the seat 19 is in the first position and open (as illustrated) 
when the seat 19 is in the second position. An annunciator 69, e.g., a 
horn is connected in the circuit. While an audible annunciator 69 is 
preferred, the term "annunciator" used herein means an audible, visual or 
tactile signalling device. 
Preferably, the circuit also has a normally-closed oil pressure switch 71 
opened by engine lube oil pressure. If such pressure declines to a level 
at which the engine 13 may be damaged, the switch 71 closes. There is also 
a parking brake switch 73 which is closed when the parking brake is set. 
In operation, it is assumed that the transmission 15 is in the power mode 
in either the forward or reverse direction (as shown in the switch symbol 
75 in FIG. 2) so that pressure switch 51 or 53 (either of which is aptly 
described as a transmission switch 50a) is closed. Closure of such switch 
51 or 53 energizes the coil 57 and opens the contact 59, making it 
impossible to energize the coil 65 of the alarm relay 61 which is in 
series with such contact 59. As a consequence, the contact 63 of the alarm 
relay 61 remains closed. 
If the seat 19 is in the second position facing forward (or generally so) 
in position for the operator 31 to drive the backhoe 11, the seat switch 
67 is open and the annunciator 69 is not energized. On the other hand, if 
the seat 19 is in the first position, i.e., rotated slightly away from 
directly forward facing (and therefore facing angularly or rearward), the 
switch 67 is closed. The annunciator 69 is energized by power flowing from 
the battery 49 through the annunciator 69, the contact 63 and the switch 
67 to ground. The apparatus 10 thus signals coincidence of transmission 
power mode and seat first position. 
Considered in another way, the apparatus 10 has a first circuit 77a 
providing a first conductive path 79a when the seat 19 is in the first 
position and a second circuit 81a providing a second conductive path 83a 
when the transmission 15 is in the power mode. The first circuit 77a 
includes the seat switch 67 and the second circuit 81a includes the 
transmission relay 55. 
FIG. 7 shows another embodiment of the apparatus 10 which, like that of 
FIG. 6, has an alarm relay 61b, a transmission relay 55b, a seat position 
switch 67 and an annunciator 69. Such apparatus 10 also has a forward 
relay 85 a reverse relay 87. Each of the relays 85 and 87 has a contact 
89, 91, respectively, to energize a respective solenoid 93 or 95, 
energization of which puts the transmission 15 into forward or reverse 
drive, respectively. 
Such circuit also has a transmission switch 50b which differs from the 
pressure switches 51, 53 (either being denominated as a transmission 
switch 50a) shown in FIG. 6 in that such switch 50b is a three-position, 
manually operated shuttle switch manipulated by the operator 31. When the 
switch 50b is in the neutral position as shown in dashed line, neither of 
the relays 85, 87 is energized and the transmission is in neutral. 
When the switch 50b is moved upward or downward (as shown in solid line), 
either the relay 85 or the relay 87 is energized and the transmission 15 
is shifted into forward or reverse, respectively. (It is to be appreciated 
that if the switch 50b is sized to carry and switch the operating current 
of the solenoids 93, 95, such switch 50b can be connected directly to such 
solenoids 93, 95; there would be no need for the intervening relays 85, 
87.) 
Like the circuit of FIG. 6, that of FIG. 7 includes a first circuit 77b 
providing a first conductive path 79b. There is also a second circuit 81b 
providing a second conductive path 83b. 
In operation, it is assumed that the shuttle-type transmission switch 50b 
is either up or down and that the transmission is in either forward or 
reverse power mode, respectively. For either position of such switch 50b, 
the coil 97 of the normally-open transmission relay 55b is energized and 
its contact 99 closed. 
Closure of the contact 99 energizes the coil 101 of the normally-open alarm 
relay 61b and its contact 103 also closes. If the seat 19 is in the second 
position (facing forward) in position for the operator 31 to drive the 
backhoe 11, the seat switch 67 is open and the annunciator 69 is not 
energized. 
On the other hand, if the seat 19 is in the first position, i.e., rotated 
slightly away from directly forward facing, the switch 67 is closed. The 
annunciator 69 is energized by power flowing from the battery 49 through 
the annunciator 69, the contact 103 and the switch 67 to ground. The 
apparatus 10 thus signals coincidence of transmission power mode and seat 
first position. An oil pressure switch 105 and a parking brake switch 107 
may also be included. 
The inventive method includes, in either order or simultaneously, the steps 
of establishing a first conductive path 79 when the seat 19 is in the 
first position and establishing a second conductive path 83 when the 
transmission is in the power mode. Such method also includes the step of 
annunciating a signal when the conductive paths 79, 83 are established 
simultaneously. 
In more detailed aspects, the step establishing a first conductive path 79 
includes actuating a seat switch 67 and the step establishing a second 
conductive path 83 includes actuating a transmission switch 50. 
Preferably, the step establishing a second conductive path 83 also 
includes actuating a transmission relay 55. 
In one preferred version of the method, the seat switch 67 is of the type 
having contacts closed when the seat 19 is in the first position. 
Transmission relay actuating includes closing a contact in series with the 
annunciator 69 and the seat switch 67. Electrical power thereby flows 
through the seat switch 67, the closed contact and the annunciator 69 and 
the operator 31 is alerted that the transmission 15 is in the power mode 
and the seat 19 is out of its second or "machine-driving" position. 
So that the apparatus 10 is not inordinately "touchy," it is preferred that 
the axis 35 of the seat 19 be required to be angularly, rotationally 
displaced from the reference axis 37 by at least a few degrees before the 
seat switch 67 is actuated. As shown in FIG. 3, such angular displacement 
is represented by angle "A" and a value of "A" of about 15.degree. to 
20.degree. is preferred. 
While the principles of the invention are described in connection with 
specific embodiments, it should be understood clearly that such 
embodiments are exemplary and not limiting.