U.S. patent number 3,602,375 [Application Number 04/797,757] was granted by the patent office on 1971-08-31 for piggyback load handling crane.
This patent grant is currently assigned to Koehring Company. Invention is credited to Edwin O. Martinson.
United States Patent |
3,602,375 |
Martinson |
August 31, 1971 |
PIGGYBACK LOAD HANDLING CRANE
Abstract
A crane for transferring a semitrailer, cargo container, or
other piggyback load from the road to a rail car, and vice versa,
is equipped with parallel horizontal tracks and a load suspension
system which is shiftable bodily back and forth on the tracks
between the road side and the rail side of the crane. T load
suspension system comprises a pair of back and forth movable
carriages on the tracts, a load supporting truss between the
carriages, and lift arms pivoted on the opposite ends of the truss
and bearing at their free ends upon the carriages.
Inventors: |
Martinson; Edwin O. (Milwaukee,
WI) |
Assignee: |
Koehring Company (Milwaukee,
WI)
|
Family
ID: |
25171732 |
Appl.
No.: |
04/797,757 |
Filed: |
February 10, 1969 |
Current U.S.
Class: |
212/198;
294/81.54; 414/542; 212/73; 414/392 |
Current CPC
Class: |
B60P
1/6445 (20130101); B65G 63/045 (20130101) |
Current International
Class: |
B60P
1/64 (20060101); B65G 63/00 (20060101); B65G
63/04 (20060101); B66c 005/02 () |
Field of
Search: |
;212/10-14,18,124,125,40,49 ;214/38,42,75,75H |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Hornsby; Harvey C.
Claims
It is claimed and desired to secure by Letters Patent:
1. A crane adapted to laterally transfer a load from one side of
the crane to the other, said crane comprising:
a mobile chassis having longitudinal ends;
a pair of generally T-shaped supports each having a vertical post
assembly with a horizontal crossbeam fixed adjacent the upper end
of said vertical post assembly;
first and second mounting means for mounting the lower ends of said
post assemblies in an upstanding position adjacent said chassis
ends in a spaced, generally parallel relation to each other with
said crossbeams extending traversely of the longitudinal axis of
said chassis, one of said mounting means including pivotal means
for pivotally mounting one of said T-shaped supports on one of said
chassis ends;
a motor means for moving one of said T-shaped supports about its
pivot;
an overhead assembly spanning said support comprising:
first and second carriages operatively mounted, respectively, on
each of said crossbeams for horizontal movement traversely of said
chassis;
a generally horizontally extending load carrying truss operatively
connected to said carriages;
first and second lift means operatively interposed, respectively,
between said first carriage and one end of said truss in vertical
and horizontal load transmitting relation to said first carriage
and between said second carriage and the other end of said truss in
vertical and horizontal load transmitting relation to said second
carriage, said first and second lift means each comprising a lift
arm, a hinge joint at one end of said lift arm and an articulated
joint at the other end thereof; a power cylinder connected between
said truss and lift arm to provide up and down movement to said
truss, articulated hinge joints connecting said lift arm with
opposite ends, respectively, of said truss in up and down swingable
relation thereto, and said articulated joints being associated,
respectively, with said first and second carriages and operative to
accommodate up and down movement and horizontal angular
displacement of said lift arms relative to said carriages.
2. A crane according to claim 1 further comprising a pair of
counterweights mounted, respectively, on said supports for back and
forth movements traversely of said chassis, and power transmitting
means operatively connecting said counterweights, respectively,
with said carriages so that movement of said carriages in one
direction causes movement of said counterweights in the opposite
direction, and vice versa.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to load handling apparatus and it is
concerned more particularly with a crane for handling piggyback
loads, that is, loads such as semitrailers and cargo containers
which, in accordance with a widely adopted practice of the shipping
industry, are transported by truck for short haulage and by rail
car for long haulage.
2. Description of the Prior Art
The time between one load pickup and the next, that is, the cycling
time of a piggyback load handling crane, should obviously be as
short as possible. In this respect, however, difficulties have been
encountered during the past. If the load is suspended by cables of
a hoist system, as it usually is in heretofore known piggyback load
handling cranes, inertia forces due to rapid load handling may
cause the load to pendulate, which is undesirable because it makes
spotting of the load difficult and prolongs the cycling time.
Another aspect of piggyback loading is the traffic at the railroad
yards where trains are to be loaded and unloaded. This involves the
maneuvering of semitrailers into and out of pickup positions along
a train. The preferred practice in this connection is to place the
semitrailers upon a paved strip along the track and at some
distance from it so that hauling trucks for the semitrailers may
readily move back and forth along the paved strip between a row of
parked semitrailers and the train. Further, the semitrailers, when
in pickup position, should stand obliquely with respect to the
railroad track, that is, at an acute angle which will make it
possible for a truck to pull out any selected semitrailer from
between adjacent trailers without moving the latter.
To taker care of these requirements gantry-type cranes have been
employed during the past. These cranes, however, are relatively
bulky and expensive, and attempts have heretofore been made to
provide a platform type crane for the same purpose which would have
the advantage of being more compact and less costly than the gantry
type. However, such attempts as were made during the past have not,
in all respects, been entirely successful.
A relatively wide range of horizontal angularity control of the
load is important for the mentioned oblique orientation of the
semitrailers in their pickup positions. While platform type cranes,
as heretofore known, have been able to turn the load horizontally
to some extent, they have not been adequate to afford the
relatively wide range of angularity which is required for the most
efficient selective handling of semitrailers from a parked row
along a railroad train.
Another shortcoming of side loading cranes, as heretofore
suggested, has been that it was difficult to fully safeguard their
lateral stability under adverse operating conditions as, for
instance, under crosswinds or under inertia forces set up by rapid
load transfer from one side of the crane to the other.
SUMMARY OF THE INVENTION
Generally it is an object of the invention to provide an improved
platform type piggyback load handling crane.
More specifically, it is an object of the invention to provide an
improved platform type crane which will be capable of transferring
a piggyback load from the road to a rail car, or vice versa,
rapidly but without causing the load to pendulate at the end of the
transfer operation.
A further object of the invention is to provide a piggyback load
handling crane having a platform type mobile chassis and an
overhead load suspension system which will provide a relatively
wide range of horizontal angularity control of the load.
A still further object of the invention is to provide an improved
platform type crane incorporating a relatively simple and highly
efficient counterbalancing system for its load handling
mechanism.
These and other objects and advantages will be apparent from the
description herein of a preferred embodiment of the invention
illustrated by the accompanying drawings, wherein
FIG. 1 is a side elevation of a platform type piggyback load
handling crane; the crane being shown in full lines in a load
pickup condition, and in broken lines in an intermediate load
lifting condition;
FIG. 2 is a view similar to FIG. 1 and shows the crane in a maximum
load lifting condition;
FIG. 3 is an end view on line III--III of FIG. 1 and shows a
piggyback load in full lines at the road side and in broken lines
at the rail side of the crane;
FIG. 4 is a sectional view taken on line IV--IV of FIG. 2;
FIG. 5 is a top view of FIG. 1 and of part of a rail car and a
railroad track;
FIG. 6 is a view similar to FIG. 5 and shows the overhead assembly
of the crane in an oblique position.
FIG. 7 is an enlarged elevational view of a carriage and
counterweight;
FIG. 8 is a top view of FIG. 7;
FIG. 9 is an enlarged elevational view partly in section, showing
parts at one end of the crane; and
FIG. 10 is an enlarged detail view of an articulated joint
assembly.
The principal components of the crane shown in the drawings are: a
mobile chassis generally designated by the reference character 1;
opposite end assemblies on the chassis generally designated by the
reference characters 2 and 3, respectively; and an overhead
assembly spanning the end assemblies and generally designated by
the reference character 4.
The mobile chassis 1 comprises a horizontal, longitudinal main beam
5 mounting laterally extending horizontal frame work 6, a front
axle 7 supported on steerable, power driven front wheels 8 and 9; a
rear axle 11 supported on steerable, power driven rear wheels 12
and 13, and transverse front and rear box frames 14 and 16 secured
to the front and rear ends, respectively, of the main beam 5.
The mobile chassis is stabilized against lateral tilting by ground
engaging, laterally projectable and retractable front outriggers
17, 18, and rear outriggers 19, 21 of conventional construction
which are mounted on the front and rear box frames 14 and 16,
respectively.
The rearward end assembly 2 comprises a generally T-shaped support
which is mounted in a fixed, transverse, upstanding position at the
rear end of the mobile chassis 1. As shown in FIGS. 1 and 3, a
V-shaped post assembly 22 is pivoted at 23 on one end of the rear
box frame 16, and an identical V-shaped post assembly 24 is pivoted
coaxially with the post assembly 22 at the other end of the rear
box frame 16. The post assemblies 22 and 24 are rigidly
interconnected by transverse and inclined cross braces 26. The
upper ends of the post assembly 22 are pin connected at 27 and 28
to depending lugs at one side of a downwardly tapered box part 29,
and the upper ends of the post assembly 24 are similarly connected
to the other side of the box part 29.
The post assemblies 22, 24 and associated bracing 26, together with
the box part 29 form the stem portion of the T-shaped rear support
on the chassis 1. The top part of the T is formed by a long hollow
crossbeam 31 of substantially square cross section. The box part 29
of the stem has upwardly diverging sides 32 and 33 and it is
integrally connected, as by welding along its top edges, with the
lower side of the crossbeam 31.
The T-shaped support comprising the post assemblies 22, 24, bracing
26, box part 29 and crossbeam 31 is normally secured against
forward or backward pivoting on the rear box frame 16 by a brace 34
of fixed length. One end of the brace 34 is pin connected at 36
with the main beam 5 of the chassis 1, and the other end of the
brace is pin connected to the box part 29. The crossbeam 31 mounts
a pair of parallel rails 37, 38 (FIG. 9) on its upper side on which
a carriage, generally designated by the reference character 39, is
movable back and forth transversely of the chassis 1, as will be
described more fully hereinbelow. For purpose of dismantling the
crane the unit comprising the box part 29 and crossbeam 31 may
readily be removed from the chassis by means of an auxiliary crane
after the box part 29 has been disconnected from the upper ends of
the post assemblies 22, 24 and from the upper end of the brace
34.
The forward end assembly 3 on the chassis 1 includes a T-shaped
support which is an opposite hand duplicate of the T-shaped support
of the rearward end assembly 2. Primed reference numerals
corresponding to the unprimed reference numerals for the parts of
the T-shaped support at the rear designate the same parts of the
T-shaped support at the front end of the mobile chassis 1. A
carriage 39' which is an opposite hand duplicate of the carriage 39
is movable back and forth transversely of the chassis 1 on rails
37', 38' of the T-shaped support at the front end of the
chassis.
In lieu of the solid brace 34 which secures the rearward T-shaped
support in an upright position on the chassis 1, a telescopic link
41 has a pivotal connection 42 at its lower end with the main beam
5 of the chassis, and the upper end of the link 41 has another
pivotal connection with the box part 29' of the forward T-shaped
support. The relatively reciprocable elements of the brace 41 are
normally free to telescope. For purposes of dismantling the crane
or erecting it a lockup pin, not shown, may be inserted through
registering holes 43 in the upper and lower parts of the brace 41
so that the forward T-shaped support will be temporarily secured in
the upright position in which it is shown in full lines in FIG.
1.
The overhead assembly 4 between the end assemblies 2 and 3, as best
shown in FIG. 2, comprises a truss 44; a rear lift arm 46 pivoted
at 47 on the rear end of the truss and bearing at its free end upon
the carriage 39; a front lift arm 46' pivoted at 47' on the front
end of the truss and bearing at its free end upon the carriage 39';
rear and front crane trolleys 48, 48' on the truss; and rear and
front pairs of grapple arms 49, 51, (FIG. 3), and 49', 51' (FIG. 4)
suspended from the trolleys 48 and 48', respectively.
The truss 44 is of lattice type construction and of uniform width
from end to end (FIG. 5). The height of the truss is uniform at an
elongated midportion (FIG. 1) and diminishes gradually at its
opposite ends. As shown in FIG. 4, the truss comprises tubular top
beam 52, 53 and tubular bottom beams 54, 56 which extend parallel
to each other in the longitudinal direction of the truss and are
interconnected by transverse braces 57 (FIG. 5) and vertical lacing
58 (FIG. 1).
The lift arm 46 is best illustrated by FIGS. 7, 8 and 9. It
comprises a pair of relatively long, parallel side beams 59, 61; a
cross tube 62, to which the beams 59, 61 are secured, as by
welding, so as to extend radially therefrom in transverse alignment
with each other; and a pair of relatively short parallel extension
plates 63, 64 which are secured, as by welding, to the opposite end
faces of the cross tube 62 so as to extend radially therefrom in
transverse alignment with each other and in downward inclined
relation to the beams 61, 62. The free ends of the beams 59, 61 are
pivotally connected at 47 on a horizontal transverse axis with the
rear end of the truss 44.
Up and down adjustment of the lift arm 46 about its pivot axis 47
is effected by two hydraulic rams 66, 67 which are mounted on the
truss 44 on a common transverse pivot axis 68 above the pivot axis
47, the ram 66 having a pivot connection 69 (FIG. 9) with the side
beam 59 of the lift arm 46, and the ram 67 having a corresponding
pivot connection with the side beam 61.
Midway between the extension plates 63, 64 of the lift arm 46 a
third extension plate 71 is secured to the cross tube 62, the free
ends of the extension plates 63, 64, 71 being transversely aligned
with each other on an axis 72 (FIG. 9), which extends parallel to
and is spaced radially from the cross tube 62. In the assembled
condition of the crane, as shown in FIG. 1, the cross tube 62 and
the extension plates 63, 64, 71 overlie the carriage 39 and are
connected in load transmitting relation thereto. The carriage
comprises a horizontal frame including longitudinal side members
73, 74 (FIG. 8), end crossmembers 76, 77 and intermediate
crossmembers 78, 79. Pairs of double flanged wheels 81, 82 and 83,
84 support the carriage frame at its opposite ends on the rails 37
and 38. The flanges of the wheels 81 and 83 straddle the rail 38,
and the flanges of the wheels 82 and 84 straddle the rail 37 so
that horizontal thrust forces acting in the longitudinal direction
of the mobile chassis 1 will be transmitted from the T-shaped
support of the end assembly 2 to the carriage 39, and vice
versa.
A vertical load transmitting shoe 86 is pivotally mounted on the
axis 72 at the free end of the extension plate 63 and a similar
shoe 87 is pivotally mounted on the axis 72 at the free end of the
extension plate 64. The shoes 86, 87 slidably bear upon the end
members 76, 77 of the rear carriage 39. In FIG. 9 the end member 76
is shown inclined relative to the top surface of the crossbeam 31,
and the end member 77 is similarly inclined, to compensate for the
slight backward tilt at which the T-shaped support of the rear end
assembly 2 is normally positioned as shown in FIG. 1.
The connection between plate 71 and the carriage 39 is shown in
detail in FIG. 10. It comprises a yoke 88 and a self-aligning ball
bushing 89. A pivot pin 91 for the yoke 88 is mounted on the
crossmembers 78, 79 of the carriage frame, and a pin 92 on the
swinging end of the yoke mounts the inner ring 93 of the ball
bushing 89. The outer ring 94 of the ball bushing is fitted into a
circular bore at the free end of the extension plate 71. Retainer
rings 96, 97 bear against the axially opposite ends of the outer
ball ring 94 and are secured to the plate 71 by screws 98. The
inner ball ring 93 is centered between the arms of the yoke 88 by
tubular spacers 99.
The ball bushing 89 and associated parts, in conjunction with the
slide shoes 86, 87, afford an articulated joint between the lift
arm 46 and the carriage 39 which accommodates up and down movement
and horizontal angular displacement of the lift arm 46 relative to
the carriage 39. At the other end of the lift arm 46 the pivot
connections of the side beams 59, 61 with the rear end of the truss
44 of the axis 72 afford a hinge joint which connects the lift arm
46 in up and down swingable relation with the truss.
A mechanism for moving the carriage 39 on the rails 37, 38 from one
end of the crossbeam 31 to the other, and vice versa, is shown in
FIGS. 7, 8 and 9. It comprises a cable 101 which is wrapped around
a driving drum 102 on the frame of the carriage 39, and which is
anchored at its opposite ends on the crossbeam 31, one end of the
cable having a plug 103 which is bolted to one end of the beam 31,
and the other end of the cable having another plug, not shown,
which is bolted to the other end of the beam 31. A reversible
hydraulic motor 104 on the carriage 39 drives a speed reducing
transmission 106 which has a two-way driving connection with the
drum 102. Rotation of the drum in opposite directions causes back
and forth movement of the carriage 39 along the top of the T-shaped
support at the rear end of the chassis 1.
Reciprocably mounted within the crossbeam 31 is a counterweight 107
which is supported on four wheels 108. Running shoulders 109 (FIG.
9) for the wheels 108 extend along the inside bottom wall of the
beam 31 throughout its length. Power transmitting means operatively
connecting the counterweight 107 with the carriage 39 comprise two
cables 111 and 112, one for pulling the counterweight to the right
in FIG. 7 when the carriage 39 moves to the left, and the other for
pulling the counterweight to the left when the carriage moves to
the right.
As shown in FIG. 9, the carriage 39 has depending brackets 113 and
114 at its opposite sides, and rollers 116, 117 at the lower ends
of the brackets 113 and 114 underlie overhanging flange portions of
the rails 37, 38. The carriage will thus be kept from overturning
sidewise on the crossbeam 31. The bracket 114 also serves to anchor
the cables 111, 112 to the carriage 39. A turnbuckle 118 is
connected at one end with the bracket 114 and at its other end to
the cable 111. From the turnbuckle 118 the cable extends around a
sheave 119 at the right end of the beam 31 and into the beam 31. A
plug 121 at the other end of the cable is bolted to the right end
of the counterweight 107, as viewed in FIG. 7. Similarly, a
turnbuckle 122 is connected at one end with the bracket 114 and at
its other end with the cable 112. From the turnbuckle 122 the cable
112 extends around a sheave 123 (FIG. 5) at the left end of the
beam 31, and a plug 124 (FIG. 8) at the other end of the cable 112
is bolted to the left end of the counterweight 107, as viewed in
FIG. 8. The cables 111 and 112 are so dimensioned in length that
adjustment of the carriage 39 to its center position between the
ends of the beam 31 will also place the counterweight 107 into a
center position between the ends of the beam 31. Movement of the
carriage 39 along the crossbeam 31 in one direction will
automatically move the counterweight 107 in the opposite direction,
and when the carriage 39 has travelled to one end of the beam 31
the counterweight 107 will have travelled to the other end, and
vice versa.
The front end of the truss 44 has a lift connection with the
T-shaped support of the front end assembly 3, which is in all
respects identical with the hereinbefore described lift connection
of the rear end of the truss with the T-shaped support of the rear
end assembly 2. Primed reference numerals corresponding to the
unprimed reference numerals for the rearward lift connection
designate the same parts of the forward lift connection.
Upward swinging of the lift arms 46, 46' about their pivot axes 47,
47' by full contraction of the lift rams 66, 67 and 66' , 67'
lowers the truss into the load pickup position in which it is shown
in full lines in FIG. 1.
Expansion on the rams 66, 67 and 66', 67' from their fully
contracted conditions raise the truss and also increases the
relative spacing between the carriages 39, 39' in the longitudinal
direction of the chassis. As a result, the front end assembly 3
will be tilted forward from the full line position in which it is
shown in FIG. 1; and a position of maximum forward tilt will be
attained when the truss has been raised to the intermediate
position in which it is shown in broken lines in FIG. 1. Continued
expansion of the lift rams 66, 67 and 66', 67' which raises the
truss from the intermediate position to the load transfer position
illustrated by FIG. 2 causes the front end assembly 3 to tilt back
to the upright position in which it is shown in FIG. 2, and which
is substantially the same as in FIG. 1.
The forward crane trolley 48' on the truss 44 comprises a frame
which, as shown in FIG. 4, surrounds the truss and is supported
thereon for sliding movement in lengthwise opposite directions.
Angle iron members 126, 127 (FIG. 4) at opposite sides,
respectively, of the trolley have horizontal flanges overlying the
top beams 52 and 53 of the truss, and a cross tube 128 underlying
the truss 44 is connected with depending flanges of the angle irons
52, 53 by brace assemblies 129 and 131.
A double acting hydraulic shift ram 132' for the trolley 48' is
connected at its barrel end with a bracket 133' at the upper side
of the trolley, and the piston rod of the shift ram 132' is
connected with a bracket 134' at the upper side of the truss 44.
Contraction of the shift ram 132' moves the trolley 48' to its
forward end position on the truss in which it is shown in FIGS. 1
and 2, and expansion of the shift ram 132' moves the trolley to a
rearward end position.
The cross tube 128 of the trolley 48' shiftably supports the
forward grapple arms 49' and 51' for translatory horizontal
movement toward and away from each other; and the cross tube 128
also supports the grapple arms 49' and 51' for pivotal movement at
right angles to their translatory movement. In order to provide for
such translatory and pivotal movement of the grapple arms,
elongated tubular side journals 136, 137 (FIG. 4) are connected,
respectively, to the grapple arms at their upper ends, and are
telescopically and rotatably supported within the opposite end
portions of the tube 128.
Actuating means for the grapple arm 49' comprise a double acting
hydraulic shift ram 138 within the cross tube 128, and a double
acting hydraulic swing ram 139' at the same side of the trolley 48'
as the grapple arm 49'.
The shift ram 138 is anchored at its barrel end on a vertical pin
within the tube 128 adjacent the longitudinal vertical midplane of
the truss, and the piston rod of the ram is connected to the inner
end of the journal 136. Contraction of the ram 138 adjusts the
grapple arm 49' to its limit of translatory inward movement as
shown in full line in FIG. 4, and expansion of the ram 138 adjusts
the grapple arm 49' to its limit of translatory outward movement as
shown in broken lines in FIG. 4.
The swing ram 139' is universally connected at its barrel end with
a bracket arm 141 of the brace assembly 129 and the piston rod of
the swing ram is universally connected with the grapple arm 49' at
a radial distance from the axis of the tubular journal 136.
Contraction of the swing ram 139' lowers the grapple arm 49' to the
vertical position in which it is shown in FIG. 1 irrespective of
the lateral position to which the grapple arm is adjusted by the
shift ram 138. Conversely, expansion of the swing ram 139' raises
the grapple arm 49 to the approximately horizontal broken line
position in which it is shown in FIG. 1, regardless of its lateral
adjustment by the shift ram 138.
A shift ram 49'. corresponding to the shift ram 138, and a swing
ram 143' corresponding to the swing ram 139' are connected to the
tubular journal 137 and to the grapple arm 51' for translatory
shifting and vertical swinging of the latter relative to the crane
trolley 48', the same as the grapple arm 49'.
The foregoing explanations with respect to the front trolley 48',
analogously apply to the rear trolley 48. A shift ram 132 is
connected at its opposite ends to brackets 133 and 134 on the rear
trolley frame and on the truss 44, for shifting the rear trolley 48
back and forth longitudinally on the truss. Shift and swing rams
for the grapple arms 49, 51 on the rear trolley 48 are duplicates
of the shift rams 138, 142 and 139', 143' on the front trolley, the
swing ram 139 corresponding to the swing ram 139' being shown in
FIG. 2.
An operator's cab 144 (FIGS. 1 and 2) is mounted at the rear end of
the chassis 1, and it will be understood that the chassis also
carries a power plant, not shown, including an internal combustion
engine, hydraulic pumps and associated hydraulic circuits for
actuating hydraulic motors of the chassis running gear and of
various other components of the crane. A control console in the cab
144 with the necessary hydraulic valves, not shown, enables an
operator in the cab to conveniently perform and observe all
functions of the crane.
A semitrailer 146 of conventional construction is shown in FIG. 1
positioned on a pavement strip which may extend along a railroad
track 147, shown in FIGS. 3 and 5. In FIG. 5 the semitrailer
extends parallel to the railroad track, and the crane chassis 1
with the wheels 9-13 is located between the semitrailer 146 and a
flat car 148 on the railroad track 147. The transverse spacing of
the semitrailer from the track is also sufficient to permit
adjustment of the front outriggers 17, 18 and rear outriggers 19,
21 to their fully extended positions in which they bear upon the
pavement at substantial lateral distances beyond the tread spacing
of the crane front supporting wheels 8, 9 and beyond the tread
spacing of the crane rear supporting wheels 12, 13.
In order to pick up the semitrailer 146 from the position in which
it is shown in FIGS. 1, 3 and 5, the overhead assembly 4 of the
crane is first manipulated into the position in which it is shown
in FIGS. 1 and 3 and in which the front and rear grapple arms 49',
51' and 49, 51 straddle the body of the semitrailer and grip it as
shown in full lines in FIG. 4. Pressure fluid is then admitted to
the rear lift rams 66, 67 and front lift rams 66', 67' so that they
will expand and cause the overhead assembly 4 and semitrailer 146
to assume the raised position at the roadside of the crane in which
they are shown in FIG. 2. In that condition of the crane the
counterweights 107, 107 will be positioned at the railside of the
crane and substantially balance the weight of the overhead assembly
4.
Next, the hydraulic motor 104 on the carriage 39 and the
corresponding hydraulic motor on the carriage may be energized to
transfer the truss and semitrailer to the railside of the crane and
into a position from which the semitrailer may be lowered straight
down upon the flat car 148 on the railroad track 147. Such transfer
may be effected rapidly, and when the carriages are stopped at the
end of the run the semitrailer will stop instantaneously without
pendulating because of its laterally rigid connection with the
carriages by means of the grapple arms, trolleys and lift arms 46,
46'.
The flat car 148 has a stanchion 149 and the semitrailer 146 has a
coupling stud 151 which may be engaged with the stanchion when the
semitrailer is lowered upon the flat car. The shift rams 132, 132'
on the truss 44 may be adjusted to manipulate the semitrailer into
a rearwardly shifted position before it is lowered by contraction
of the lift rams 66, 67 and 66', 67'; and after the wheels of the
semitrailer have come to rest on the flat car the shift rams 132,
132' may be activated to shift the trailer forward and thereby
engage the coupling stud 151 with the stanchion 149. The stud may
then be locked on the stanchion by means of a suitable latch
mechanism, not shown.
After the semitrailer has been lowered upon the flat car the
grapple arms 49, 51 and 49', 51' are disengaged from it by
expansion of the shift rams 138, 142 as indicated in broken lines
in FIG. 4, and by expansion of the swing rams as indicated in
broken lines in FIG. 1. Thereafter the overhead assembly 4 may be
raised slightly and moved back to the road side of the crane for a
new pickup.
Unloading a semitrailer from a flat car may obviously be
accomplished by reversing the described loading procedure, except
that in bringing a semitrailer from the railside to the roadside of
the crane the semitrailer may be maneuvered into an oblique
position as illustrated by FIG. 6 by correspondingly controlling
the travel of the carriages 39, 39'. Depositing the semitrailers
obliquely, that is, at a substantial horizontal angle relative to
the railroad track is a well-known expedient and a common
requirement in the handling of piggyback loads. When a row of
semitrailers are parked obliquely side by side along the railroad
track a hauling truck may move into the space between the track and
the trailers and be coupled to any selected one of them and pull it
out of the row without moving any of the adjacent semitrailers.
In the herein disclosed crane the requirement for a relatively wide
range of horizontal angular adjustment of a semitrailer or other
piggyback load suspended from the truss 44 is afforded by the
articulated connections of the lift arms 46, 46' with their
respective carriages 39, 39 and by the back and forth tiltable
mounting of the T-shaped support of the front end assembly 3.
* * * * *