Single engine excavator capable of railroad use

A material handling vehicle is provided which is capable of operation on the highway, off-road and on railroad tracks. The vehicle includes a lower truck chassis having an engine and a first operator's cab and an upper structure which includes an upper structure operator's cab and a material handling implement. In the travel mode of operation, the engine is directly connected to the torque converter of a powershift transmission to provide a rotational output to the drive wheels. In the off-road or remote operating mode of the excavator, the transmission is controlled so as to prohibit the connection between the torque converter and the transmission gears. However, a power take-off on the transmission is coupled to a hydraulic pump which provides hydraulic fluid under pressure to a hydraulic motor which, in turn, may provide rotational power to a secondary input to the transmission to provide drive power. In the railroad operating mode of the present invention, the engine is coupled by means of the torque converter to the transmission to provide driving power. In addition, the engine is coupled to the hydraulic pump to provide hydraulic fluid under pressure to power the excavator functions. The upper structure cab includes two throttle controls for controlling engine speed while operating in the remote operating mode.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to material handling vehicles and, more 
particularly, to a material handling vehicle for use in highway, off-road 
and railroad applications which includes a single engine that may be 
controlled from multiple operator's stations. 
2. Description of the Prior Art 
Heretofore, material handling vehicles such as excavators or cranes have 
been developed for use on highways and on railroad tracks. Such vehicles 
typically include a lower or truck chassis on which there is pivotally 
mounted an upper structure that supports a material handling implement. 
The lower chassis is capable of being driven over the road or highway 
under the control of an operator in a cab mounted on the lower chassis. 
The lower chassis additionally includes deployable railroad wheels to 
guide the vehicle's movement along railroad tracks with driving power 
being provided by the engagement of the drive wheels of the lower chassis 
with the railroad tracks. An upper structure is mounted on the lower 
chassis by a swing bearing through which a center pin extends for relative 
movement with respect to the lower chassis. An upper structure operator's 
cab is provided on the upper structure as well as a material handling boom 
and implement. During operation on railroad tracks, an operator in the 
upper structure operator's cab can control movement of the lower chassis 
and also of the material handling implement. 
Previously, in order to provide power for remote operation under the 
control of an operator in the upper structure cab of both the 
manipulations of the material handling implement as well as the movement 
of the vehicle along the railroad tracks, two separate engines were 
required. One engine was mounted on the lower chassis and controlled the 
highway operation of the vehicle. A separate engine was mounted on the 
upper structure and provided power to the material handling mechanism as 
well as powering, through a hydraulic pump and motor, the motion of the 
lower chassis. 
As is well known in the art, the previously unavoidable requirement of two 
separate engines, one on the truck chassis and one on the upper structure, 
was fraught with a host of disadvantages. For example, in the prior art 
construction requiring two separate engines, the additional weight and 
cost of the auxiliary engine itself as well as duplicate fuel tanks, 
radiators, batteries and charging systems, air compressors and dryers, 
power steering pumps, air cleaners and exhaust systems, controls, 
shroudings and mountings, noise barriers, engine gauges, etc. are 
incurred. In addition, duplicate maintenance functions are involved in a 
two-engine vehicle and operating costs are necessarily increased. Further, 
the inclusion of the second engine and hydraulic reservoir on the movable 
upper structure raised the center of gravity of such material handling 
vehicles. Such a high center of gravity imposed engineering and operating 
restrictions which were considerable. 
It is apparent that for a material handling vehicle to be effective for 
railroad applications, it must have the capability of pulling railroad 
cars along the tracks. For example, in the case of an excavating vehicle, 
the apparatus should have the capability of pulling a hopper car along the 
tracks which may be filled with material removed by the excavator. Prior 
art two-engine excavating vehicles provided alternative means for powering 
the vehicle's movement along railroad tracks. In one operating mode, an 
operator in the lower operator's cab could drive the lower chassis while 
pulling a railroad car. While this mode of operation provided sufficient 
power to allow the vehicle to pull a railroad car, an operator who was in 
the upper cab would have to move to the lower cab to control vehicle 
travel on the railroad tracks. If excavating was to be performed during 
travel on railroad tracks, because all excavator functions were controlled 
from the upper structure operator's cab, a second operator in the upper 
structure cab was required to manipulate the material handling implement 
under the power of the upper structure engine. As such, in that operating 
mode, both engines were running and two operators were required. If only a 
single operator were present in the upper structure operator's cab, and 
the upper structure engine was actuated to provide power to a hydraulic 
pump to power the material handling implement functions as well as power 
the vehicle by a hydraulic motor, the power required to move a railroad 
car would not be available. Accordingly, prior art two-engine excavators 
have proven unsuitable for use in railroad applications. 
The assignee of the present invention has developed an alternative method 
of powering a material handling vehicle for use in highway and off-road, 
but primarily not railroad, applications. This apparatus, disclosed in 
U.S. patent application Ser. No. 807,616, filed Dec. 11, 1985, now U.S. 
Pat. No. 4,705,450, relates to a material handling vehicle having a lower 
chassis which includes an engine and a first operator's cab. An upper 
structure is pivotally mounted on the lower chassis and includes an upper 
structure operator's cab and a material handling implement. Such a vehicle 
may be powered in one of two ways. First, an operator in the lower cab may 
control the engine so as to drive through a powershift transmission to 
power the drive wheels of the vehicle. If operation is intended from the 
upper structure operator's cab, by the proper control of the powershift 
transmission, the engine is effectively disconnected from the transmission 
and, instead, drives a hydraulic pump. The hydraulic pump may power the 
excavator functions and supply hydraulic fluid under pressure to a 
hydraulic motor. The hydraulic motor may then be caused to drive a 
secondary input into the powershift transmission to cause it to generate a 
rotational output effective to drive the vehicle's drive wheels. 
However, such a vehicle also suffers shortcomings when considered for use 
in railroad applications. Only two modes of operating and powering such a 
vehicle would be possible in a railroad application. In one operating 
mode, an operator in the lower truck cab could drive the vehicle with the 
engine directly coupled to the transmission to power the vehicle. In this 
mode, sufficient power would be available to tow a railroad car. However, 
no excavator functions would be possible. In an alternative operating 
mode, an operator in the upper cab could control the movement of the 
vehicle under driving power provided by the engine through the hydraulic 
pump and motor into the transmission. However, because of the limited 
capacity of the hydraulic motor, the vehicle would not possess sufficient 
power to pull a railroad car. Accordingly, while the single engine 
material handling vehicle eliminates certain of the problems associated 
with two-engine excavators, such a vehicle is unsuitable for complete 
railroad operation. 
The subject invention is directed toward an improved material handling 
apparatus which overcomes, among others, the above discussed problems with 
material handling vehicles intended for use on railroad tracks and which 
is effective to sufficiently power the vehicle to allow control by one 
operator of a vehicle having sufficient power to tow a railroad vehicle 
and control the material handling implement functions. 
SUMMARY OF THE INVENTION 
In accordance with the present invention, there is provided a material 
handling vehicle which is capable of movement on highways, off the road 
and on railroad tracks. The vehicle includes a lower chassis having an 
engine mounted thereon and a lower chassis operator's cab. The lower 
chassis horizontally pivotally supports an upper structure which includes 
an upper structure operator's cab and a material handling implement. As 
such, unlike prior art two engine material handling vehicles, the present 
apparatus requires only a single lower chassis mounted engine for powering 
movement of the vehicle on the road, off the road and on railroad tracks 
under the control of a single operator. 
When the vehicle is intended for on-road operation, an operator in the 
lower chassis operator's cab may control the operation of the engine to 
drive through a powershift transmission which, in turn, provides a 
rotational output sufficient to power the drive wheels of the vehicle. In 
the off-the-road or "remote" operating mode of the subject vehicle, an 
operator in the upper structure operator's cab may control vehicle 
movement. In that operating mode, the solenoids of the powershift 
transmission are operated so as to allow the engine to turn the torque 
converter of the powershift transmission while disengaging sufficient 
clutches thereof to cause the torque converter not to be coupled to the 
various gears of the transmission. The rotational output of the engine is 
supplied to the gears within the torque converter housing which drive, by 
means of a secondary output, a hydraulic pump by means of a first air 
cylinder actuated jaw clutch. The hydraulic pump provides pressured 
hydraulic fluid to control the material handling implement functions and 
to drive a hydraulic motor. The hydraulic motor is coupled by means of a 
second air cylinder actuated jaw clutch to a secondary rotational input to 
the transmission. The rotational power input to the transmission by the 
hydraulic motor may then power the movement of the vehicle under the 
control of an operator in the upper operator's cab. 
In accordance with the third operating mode of the present invention, an 
operator situated in the upper operator's cab may control the movement of 
the vehicle on railroad tracks. Due to the drive mechanism described 
below, the single engine apparatus possesses sufficient drive power to 
pull a railroad car. In the third or "railroad" operating mode, the engine 
drives the torque converter which is coupled to the gears of the 
powershift transmission. In addition, the first air cylinder is actuated 
so as to cause the jaw clutch to couple the hydraulic pump with the torque 
converter. Accordingly, the engine provides driving power through the 
transmission and also powers the hydraulic pump so as to provide 
pressurized hydraulic fluid for powering the material handling implement 
functions. 
In order to control the vehicle from the upper structure operator's cab in 
the railroad operating mode, additional controls are provided in the upper 
structure operator's cab. In particular, an upper structure transmission 
controller is coupled to the primary transmission control box used to 
control the transmission clutch solenoids and, hence, gear range. In 
addition, the engine speed may be controlled from the upper structure 
operator's cab by means of two different throttle control mechanisms whose 
use is selected depending on the desired vehicle capabilities. The 
throttle controls available are either a friction detented hand throttle 
control or a spring return throttle control. If the friction detented 
actuator is selected, the upper transmission controller remains disabled 
and the transmission will remain in neutral. The friction detented 
throttle control is employed when the vehicle is in the remote operating 
mode, as well as the railroad operating mode, and the operator desires to 
manipulate the material handling implement. By virtue of the friction 
detented throttle control, the engine speed may be increased to a 
sufficient level to allow maximum power to be provided to the material 
handling implement. Alternatively, if the spring return throttle is 
selected, the upper structure transmission controller is enabled thereby 
making transmission gear selection possible. The spring return throttle is 
employed when the operator desires to move the vehicle along the railroad 
tracks. As such, the engine speed may be infinitely varied to provide the 
desired power for movement. 
Accordingly, the present invention provides solutions to the aforementioned 
problems relating to material handling vehicles intended for use in 
railroad applications. As the single engine arrangement disclosed herein 
is effective to provide the required vehicle movement and implement 
control power, the disadvantages of two-engine machines are avoided. 
Further, by virtue of the unique aspects of the railroad operating mode, 
the single engine vehicle possesses sufficient drive power to tow a 
railroad car. 
These and other details, objects and advantages of the invention will 
become apparent as the following description of the present preferred 
embodiment thereof proceeds.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now to the drawings wherein the showings are for purposes of 
illustrating the present preferred embodiment of the invention only and 
not for purposes of limiting same, the figures show a mobile material 
handling vehicle 10, which for purposes of the present Detailed 
Description of the Preferred Embodiments, will be described as an 
extensible or telescoping boom hydraulic excavating apparatus, also called 
an excavator. It is to be understood that various other forms of material 
handling apparatuses are also contemplated as being within the scope of 
the present invention. 
More particularly, and with reference to FIG. 1, there is shown a mobile 
material handling vehicle 10 which is capable of operating on railroad 
tracks 12 and of pulling a railroad car 14. The excavator 10 includes a 
lower truck chassis 16 which includes a lower operator's cab 18. The lower 
chassis 16 supports an upper structure, generally designated as 20, by 
means of a swing bearing 22 through which a center pin 24 passes such that 
the upper structure 20 is rotatable with respect to the lower chassis 16 
by means of a hydraulic swing motor (not shown). The lower chassis is 
provided with front wheels 26 and rear wheel 28, which rear wheels 28 
normally serve to drive the excavator 10. When the excavator 10 is 
employed on railroad tracks 12, a front railroad wheel assembly 30 and a 
rear railroad wheel assembly 32 are moved from a retracted position on 
lower chassis 16 to an extended position to engage the railroad tracks 12. 
In a preferred embodiment of the invention, when the front and rear 
railroad wheel assemblies 30 and 32, respectively, are moved, the front 
wheels 26 of the excavator 10 will be elevated while the rear wheels 28 
will be in engagement with the railroad tracks 12. 
The upper structure 20 includes a platform, generally indicated as 34, on 
one end of which is mounted an upper structure operator's cab 36. In 
addition, an extensible boom means, generally 38, is mounted to a boom 
support cradle 40 which construction allows boom 38 to be vertically 
pivotally movable with respect to upper platform 34 by a hydraulic 
cylinder 42. The boom 38 is preferably mounted on cradle 40 so as to be 
pivotable by a hydraulic cylinder (not shown) about an axis parallel to 
the longitudinal axis of boom 38. In addition, boom 38 is hydraulically 
extendible by means known to those skilled in the art. An excavating 
bucket 44 is pivotally attached to the free end of boom 38 so as to be 
pivotable with respect thereto by hydraulic means known to those skilled 
in the art. 
The excavator 10 disclosed herein is capable of three operating modes. In 
the first operating mode, referred to herein as the "travel mode", an 
operator in the lower cab 18 may control the movement of the excavator 10 
along a highway. In a second operating mode of the excavator 10, referred 
to herein as the "remote operating mode", an operator in the upper 
structure cab 36 may control movement of the excavator 10 on or off the 
road. In a third operating mode of the excavator 10, referred to herein as 
the "railroad mode", an operator in the upper structure cab 36 may control 
movement of the excavator 10 along railroad tracks 12. In FIGS. 2-5, the 
components of excavator 10 disposed on lower chassis 16 are shown as being 
connected above center pin 24 while, for purposes of illustration, the 
components shown below center pin 24 are disposed on the upper structure 
20. 
An engine 46 mounted on the truck chassis 16 provides power for driving the 
excavator 10 on the road, off the road and on railroad tracks 12. In 
addition, by means described hereinbelow, engine 46 provides power for 
controlling the manipulation of the hydraulic functions associated with 
the upper structure 20 and the boom 38. The engine 46 may comprise a 
suitable source of power for excavator 10 such as a Cummins engine Model 
6BT5.9 turbocharged diesel liquid cooled four-cycle in-line six cylinder 
engine. The engine 46 has a throttle regulating means 45, such as an 
injection pump, which controls the speed of engine 46. A transmission 48 
having a torque converter 50 is disposed adjacent to engine 46. An input, 
shown schematically as item 47, to torque converter 50 is powered by 
engine 46. Torque converter 50 provides two rotational outputs. One output 
drives through the torque converter to a first power input, shown 
schematically as 49, to the gears of transmission 48, shown generally as 
51. The other output provides a mechanical power take-off 52 disposed 
within the housing of torque converter 50 to provide power mechanically 
around torque converter 50. Transmission 48 will preferably comprise a 
powershift transmission such as that manufactured by Funk, Inc. as Model 
2000 which is a six-speed full powershift transmission with six speeds 
forward, three reverse and neutral. Forward motion, reverse motion and the 
gear range employed may be selected through the use of electrically 
controlled solenoids generally designated as 54, which control 
hydraulically actuated multiple disc clutches mounted within transmission 
48. The clutches are preferably hydraulically applied and spring released. 
Transmission 48 preferably has a rear facing power output 56 coupled to 
gears 51, which power output 56 by means of a drive shaft 58, can drive a 
rear axle (not shown) and, hence, the rear wheels 28. Transmission 48 also 
has a secondary power input means 57 which may also drive the gears of the 
transmission 48. 
The actuation of transmission solenoids 54 to control the direction of 
movement and gear range of transmission 48 is controlled by a transmission 
control box 60 mounted in the lower cab 18. Transmission control box 60 
includes the control logic circuitry necessary to control the solenoids 54 
to effectuate the transmission 48 operations described herein. In order to 
provide a source of pressurized hydraulic fluid for powering the hydraulic 
functions of upper structure 20 and boom 38 and for powering the vehicle 
10 in its remote operating mode, there is provided a jaw clutch 62 which 
may be operatively connected to the power take-off 52 of torque converter 
50. The rotational output of jaw clutch 62 is input into a hydraulic pump 
64. Hydraulic pump 64 preferably comprises a two-section unit. A first 
pump section of hydraulic pump 64 provides hydraulic driving fluid to a 
travel control valve, not shown, which controls the provision of 
pressurized hydraulic fluid from hydraulic pump 64 to a hydraulic motor 
66. Hydraulic motor 66 may be coupled by means of a second jaw clutch 68 
to a secondary rotational input means, shown schematicaly as 57, to 
transmission 48. The second pump section of hydraulic pump 64 provides 
hydraulic fluid under pressure for powering the swing motor for moving 
upper structure 20 relative to lower chassis 16, the actuation of 
hydraulic cylinder 42, the hydraulic means for pivoting boom 38 about its 
axis, the hydraulic means for extending and retracting boom 38 and the 
hydraulic means for pivoting bucket 44 relative to boom 38 by means known 
to those skilled in the art. 
The actuation of jaw clutches 62 and 68, the control of transmission 48 and 
of the throttle to engine 46 in the various operating modes of excavator 
10 will now be discussed. A travel/remote selector switch 70 is mounted in 
lower cab 18 and has an input voltage imposed thereon by a source 72. 
Travel/remote selector switch 70 is movable between a first position for 
employment of the vehicle 10 in its travel mode and a second position for 
use of the vehicle 10 in either the remote or railroad operating modes. A 
railroad/remote selector switch 74, which is also imposed with an input 
voltage from source 72, is provided in the lower cab 18 and is 
displaceable between a first position in which the railroad operating mode 
is selected and a second operating position for engagement of the remote 
operating mode. 
Travel/remote selector switch 70 is electrically connected to a 
double-acting first electric solenoid valve 76. Supply air under pressure 
is provided from a source, generally indicated as 78, to first air 
solenoid valve 76. A single-acting second electric solenoid air valve 80 
is electrically connected to railroad/remote switch 74 and is in pneumatic 
flow communication with air solenoid valve 76. The pneumatic output of air 
solenoid valve 76 may also be selectively supplied to a first air cylinder 
82. First air cylinder 82 is connected by means of a linkage 83 to the 
first jaw clutch 62 to control the engagement of hydraulic pump 64 with 
the power take-off 52 from torque converter 50. As such, when pneumatic 
pressure is applied to the rod end of first air cylinder 82, the first jaw 
clutch 82 is engaged while, if pneumatic pressure is applied to the barrel 
end of first air cylinder 82, the first jaw clutch 82 is disengaged. In 
addition, the pneumatic output of first air solenoid valve 76 may be 
supplied through second air solenoid valve 80 to a second air cylinder 84. 
Second air cylinder 84 is connected by means of a linkage 85 to second jaw 
clutch 68 so as to control the coupling of hydraulic motor 66 with the 
secondary rotational input 57 to transmission 48. When pneumatic pressure 
is applied to the rod end of second air cylinder 84, the jaw clutch 68 is 
disengaged while, when pneumatic pressure is applied to the barrel of 
second air cylinder 84, the jaw clutch 68 is engaged. 
When the travel/remote selector switch 70 is in its first position thereby 
selecting the travel mode, the first solenoid air valve 76 is in its first 
position. As no electrical power is supplied to railroad/remote switch 74, 
second air solenoid 80 is in its first position. In the first position of 
air solenoid valve 76, pneumatic pressure is provided from source 78 to 
the barrel side of first air cylinder 82 to cause jaw clutch 62 to be 
disengaged from power take-off 52 thereby disconnecting hydraulic pump 64 
from first power take-off 52. In addition, in the first positions of first 
and second air solenoid valves 76 and 80, respectively, pneumatic pressure 
is supplied from source 78 through first air solenoid valve 76 to second 
air solenoid valve 80 to pass to the rod side of second air cylinder 84 to 
disengage the second jaw clutch 68 from the secondary input 57 to 
transmission 48 thereby disconnecting the hydraulic motor 66 from 
transmission 48. 
When in the travel mode, a transmission selector switch 86 mounted in the 
lower cab 18 is activated (as described below) to provide an input to 
transmission control box 60 which, in turn, controls the solenoids 54 of 
transmission 48 to control its gear range. In the lower cab 18, there are 
also provided customary steering and braking controls as well as a 
throttle control 59 coupled to the throttle regulating means 45 of engine 
46. As such, when in the travel mode, the hydraulic pump 64 and hydraulic 
motor 66 are not connected to the torque converter 52 and secondary power 
input 57 to transmission 48, respectively, and an operator in the lower 
cab 18 may drive the excavator 10 controlling the engine 46 by means of 
throttle controller 59 which is coupled to throttle regulating means 45. 
In the remote operating mode of excavator 10, the travel/remote selector 
switch 70 is disposed in its second position and the railroad/remote 
selector switch 74 is disposed in its second position. Certain features of 
the remote operating mode of excavator 10 are disclosed in U.S. patent 
application Ser. No. 807,616, filed Dec. 11, 1985, the disclosure of which 
is incorporated herein by reference. When the travel/remote selector 
switch 70 is in its second position, first air solenoid valve 76 is caused 
to enter its second position thereby causing pneumatic pressure to be 
provided from source 78 to the opposite sides of first air cylinder 82. 
When railroad/remote selector switch 74 is in its second position, second 
air solenoid valve 80 is in its first position. The pneumatic pressure 
passing from second air solenoid valve 80 is provided to the barrel side 
of second air cylinder 84 to cause jaw clutch 68 to allow the coupling of 
hydraulic motor 66 with the secondary input 57 to transmission 48. In 
addition, the disposition of first air solenoid valve 76 in its first 
position provides pneumatic pressure from source 78 through air solenoid 
valve 76 to the rod side of first air cylinder 82 to cause the engagement 
of first jaw clutch 62 thereby causing the coupling of hydraulic pump 64 
with the power take-off 52 from torque converter 50. Accordingly, when the 
excavator 10 is in the remote operating mode, the hydraulic pump 64 is 
coupled to the power take-off 52 in order to provide pressurized hydraulic 
fluid to hydraulic motor 66 which is, in turn, coupled to the secondary 
input 57 to transmission 48. When the railroad/remote selector switch 74 
is in the second or remote position, the lower cab transmission selector 
86 is coupled to the potential source 72 to provide control signals to 
control box 60. In addition, when in the remote mode, the transmission 
control box 60 receives a signal from travel/remote switch 70 effective to 
cause solenoids 54 to uncouple primary transmission input 49 from the 
transmission 48 and to allow the transmission 48 to accept rotational 
input from the secondary input 57 to transmission 48 provided by hydraulic 
motor 66 to generate a rotational output to power the movement of vehicle 
10. Further, when in the remote operating mode, a first transmission 
selector 87 disposed in the upper cab 36 is energized by source 72 which 
is effective to control transmission control box 60 to select the gear 
ranges of transmission 48 by means of solenoids 54. The control of the 
throttle regulating means 45 of engine 46 when the excavator 10 is in its 
remote operating mode is discussed below. 
In the event the vehicle 10 is intended to be operated in the railroad 
operating mode, the travel/remote selector switch 70 is disposed in its 
second position and the railroad/remote selector switch 74 is disposed in 
its first position. Because the travel/remote selector switch 70 is in its 
second position, it causes the first air solenoid valve 76 to be in its 
second position. In this position, pneumatic pressure is provided from 
source 78 directly to the rod side of air cylinder 82 to cause first jaw 
clutch 62 to couple the hydraulic pump 64 with the power take-off 52. 
However, because the railroad/remote selector switch 74 is in its first 
position, it causes the second air solenoid valve 80 to be in its second 
position. In this position, second air solenoid valve 80 causes pneumatic 
pressure to be provided to the rod side of second air cylinder 84 to cause 
second jaw clutch 68 to disengage hydraulic motor 66 from the secondary 
input 57 to transmission 48. Accordingly, in the railroad operating mode 
the hydraulic pump 64 is coupled to the power take-off 52 but the 
hydraulic motor 66 is uncoupled from the secondary input 57 to 
transmission 48. 
When the excavator 10 is in the railroad operating mode, the 
railroad/remote selector switch 74 also causes an electrical signal to be 
provided to a wire 81 passing through center pin 24. Wire 81 is 
operatively connected to an air actuatable pressure switch 88 located on 
the upper structure 20. Air pressure switch 88 is normally spring biased 
to a contact position. The electrical signal from air pressure switch 88 
is coupled to an upper structure air solenoid valve 90. The pneumatic 
pressure from a source 92 is provided to a first upper structure throttle 
control 94 and a second upper structure throttle control 96. First upper 
structure throttle control 94 preferably comprises a spring return 
throttle which controls the supply of pneumatic pressure from source 92 to 
the upper structure air solenoid valve 90. However, in the event the first 
upper structure throttle control 94 is released, it will return to its 
neutral position thereby prohibiting air flow therethrough. The pneumatic 
pressure supplied through first upper structure throttle control 94 is 
provided through upper structure air solenoid valve 90, which is in its 
first position due to the closed condition of pressure switch 88, through 
the center pin 24 to control the throttle actuator 45 on the engine 46. 
The electrical signal provided through pressure switch 88 also provides an 
electrical signal by means of a control wire 97 to a secondary upper 
structure transmission controller 98. Transmission controller 98 is 
coupled through the center pin 24 to the transmission control box 60 
which, in turn, controls the solenoids 54 of transmission 48 so as to 
select the gears desired. Accordingly, when in the railroad operating 
mode, if the spring return throttle 94 is operative, it may control the 
throttle 45 of engine 46 while the second transmission controller 98 
controls the transmission 48 gear range. 
In accordance with the present invention, in the railroad operating mode an 
alternative throttle control mechanism is provided for engine 46. The 
pneumatic pressure from supply 92 is also supplied to a dig brake control 
switch 100 disposed in the upper structure operator's cab 36. The dig 
brake control switch 100 is effective to apply the pneumatic brakes of 
excavator 10 by means known to those skilled in the art. In addition, when 
the dig brake control switch 100 is actuated, it provides pneumatic 
pressure from source 92 to open the air pressure switch 88 to thereby 
prohibit actuation of the upper structure transmission controller 98. In 
addition, the fact that the air pressure switch 88 is prohibited from 
contact causes the air solenoid valve 90 to be operated by its spring 
bias. This action moves air solenoid valve 90 to a second position. 
Pneumatic pressure from supply 92 passes through second throttle 
controller 96 and is provided to upper structure air solenoid valve 90 to 
provide a pneumatic signal through the center pin 24 to control the 
throttle actuator 45 on the chassis engine 46. 
Accordingly, in the railroad operating mode, a voltage is imposed on wire 
81 to cause upper air solenoid valve 90 to move it to its first position 
to allow pneumatic pressure passing from throttle control 94 to control 
engine 46. If the dig brake 100 is applied, it provides pneumatic pressure 
to open the contacts of pressure switch 88 to move air solenoid 90 to its 
second position to thereby allow the use of throttle controller 96. 
Alternatively, when the excavator 10 is in the remote operating mode, no 
voltage is imposed on wire 81 and, hence, upper air solenoid valve 90 is 
in its first position to cause first throttle controller 94 to be 
effective. 
It will be understood that various changes in the details, materials and 
arrangements of parts which have been herein described and illustrated in 
order to explain the nature of the invention may be made by those skilled 
in the art within the principle and scope of the invention as expressed in 
the appended claims.