Method of and apparatus for removal and installation of outrigger box on cranes

A pair of fixed parallel transport rails for the outrigger box of a mobile crane are installed at the bottom of the crane chassis frame. The outrigger box is held on the chassis frame by four removable tapered pins. One jack cylinder on the outrigger box is trunnion mounted so that it can be tilted to clear the bottom of the chassis frame during removal and installation of the outrigger box. The outrigger box is equipped with transport track engaging rollers. To remove the outrigger box from the crane chassis, the box is unweighted to allow ready removal of the tapered pins. The outrigger box is then lowered until its rollers are resting on the two transport rails. A collar which retains the trunnion mounted jack cylinder of the outrigger box upright is released, and that jack cylinder is lowered to a stabilized inclined position where it can pass under the chassis frame. The outrigger box is then moved in one longitudinal direction along the transport tracks until the rollers near the end of the outrigger box having the trunnion mounted jack cylinder engage end stops on the tracks. The outrigger box is then lifted from the tracks and set aside in a desired manner.

BACKGROUND OF THE INVENTION 
In the prior art, removal of the outrigger box or housing from the chassis 
of a mobile crane is a time-consuming and laborious task. Since the fixed 
upright jack cylinders at opposite ends of the outrigger box block 
longitudinal movement of the box relative to the crane chassis, it is 
necessary to remove at least one of the extremely heavy jack cylinders 
before the outrigger box can be shifted and removed. Other methods of 
removal and installation of outrigger boxes are equally inconvenient, time 
consuming and costly. 
Accordingly, it is the objective of the present invention to provide a 
simplified, convenient and much less laborious and time consuming method 
of removing and installing outrigger boxes of cranes. A related objective 
of the invention is to modify the conventional construction of the 
outrigger assembly in such a manner that the simplified and convenient 
removal and installation of the assembly is rendered possible and 
expeditious. 
Another object of the invention is to provide a method of removal and 
installation of the outrigger box which involves only four simple 
procedures or steps carried out in sequence to remove the outrigger box, 
and carried out in reverse sequence to install the box on the crane 
chassis. 
Other objects and advantages of the invention will become apparent to those 
skilled in the art during the course of the following detailed description 
.

DETAILED DESCRIPTION 
Referring to the drawings in detail, wherein like numerals designate like 
parts, a mobile lattice crane shown in FIG. 1 includes a chassis frame 20 
on which is mounted through a turntable 21, a crane superstructure 22 
including a lattice type crane boom 23 and associated conventional 
components. A readily removable crane outrigger assembly 24 in accordance 
with the main subject matter of this invention is removably mounted 
transversely beneath the chassis frame 20 in a manner to be completely 
described. 
The outrigger assembly 24 comprises a rectangular box or housing 25 within 
which are slidably mounted in parallel relationship for movement in 
opposite longitudinal directions a pair of outrigger beams 26, each having 
a horizontal operating cylinder 27 of conventional construction connected 
therewith. Each outrigger beam 26 on its exterior end beyond the confines 
of the box 25 carries an upright jack cylinder 28, 28a. The jack cylinders 
at their lower ends have vertically extensible and retractable swivel 
extensions 29 to which are attached ground engaging feet or pads which 
have been removed from the elements 29 in the drawings. The elements 29 
and the ground engaging pads are conventional. 
In the present invention, the jack cylinder 28 is rigidly held on its 
outrigger beam 26 through conventional rigid holding means 30 carried by 
the outrigger beam. The opposite end jack cylinder 28a, however, is 
pivotally mounted on its outrigger beam 26 through trunnions 31, FIG. 11, 
which are rotatably held by conventional bearing structure 32 carried by 
the adjacent end of outrigger beam 26. 
The pivoted jack cylinder 28a is normally held upright by a rigid embracing 
collar 33, which at proper times can be released and swung open to a 
position shown in phantom lines in FIG. 9 to allow tilting of the jack 
cylinder 28a to the inclined position shown in phantom lines in FIG. 10. 
In such position, the top of jack cylinder 28a can clear the bottom of 
chassis frame 20 during the removal or installation process for the 
outrigger assembly. 
The retaining collar 33 for jack cylinder 28a is pivotally coupled to fixed 
flanges 34 by removable pins 35. One or both of these pins can be pulled, 
as desired, allowing the collar 33 to swing open or to be completely 
removed, in some cases. 
The outrigger assembly 24 is removably supported on the chassis frame 20 by 
pairs of tapered pins 36 which are installed outwardly through registering 
apertures 37 and 38 formed, respectively, in opposite side lugs 39 of the 
chassis frame 20 and opposite end upstanding plate extensions 40 of the 
outrigger box 25. The lugs 39 straddle the plate extensions 40 when 
connected therewith by tapered pins 36. The pins 36 then bear the full 
weight of the outrigger assembly 24 and are under heavy shear loads. 
An important aspect of the invention is the provision on the bottom of 
chassis frame 20 close to the opposite side walls of the assembly 24 of a 
pair of fixed parallel horizontal support and guide tracks 41 for the 
outrigger assembly 24. These guide tracks are rigid with the chassis frame 
20. At their opposite ends, the two guide tracks 41 have upright stop 
plates 42 fixed thereto, for a purpose to be described. 
On the plate extensions 40 of the outrigger assembly or box adjacent to the 
swingable jack cylinder 28a is a pair of live rollers 43 adapted to engage 
and roll along the tracks 41. The opposite end of the plate extensions 40 
similarly carry dead rollers or studs 44 also adapted to engage the tracks 
41 at proper times. 
Rigid connector elements 45 for lifting cables operated by the crane are 
fixed in the four upper corners of the outrigger assembly as shown in 
FIGS. 7 and 8. The construction of the crane and the outrigger assembly 24 
is otherwise conventional, and therefore need not be described in greater 
detail for a proper understanding of the invention. 
The method of removal of the outrigger assembly 24 from the crane chassis 
frame 20 comprises the following: 
First, as shown in FIG. 3, lifting cables 46 controlled by the crane hook 
block are attached to the connectors 45 near opposite ends of the 
outrigger assembly. Two hydraulic links which supply and return hydraulic 
fluid from the horizontal operating cylinders 27 and the jack cylinders 28 
and 28a, and one electrical conduit which supplies electrical power to the 
solenoid operated control valves in the hydraulic lines on the outrigger 
assembly, all of which have quick disconnect connectors on the ends 
thereof and which are schematically illustrated at 47 in FIG. 4 as a 
single element, are disconnected from the corresponding lines on the 
chassis frame. By means of the cables 46, the assembly is unweighted to 
relieve the shear loads on the pins 36 so that the latter can be removed, 
as shown in FIGS. 2 and 12, toward the center of the outrigger assembly. 
Once removed, the outrigger assembly is carefully lowered by the cables 46 
until the live rollers 43 and dead rollers 44 rest on and are supported by 
the guide tracks 41. 
Secondly, one or both of the pins 35 are pulled so that the collar 33 can 
be swung open or totally removed. The adjacent jack cylinder 28a is then 
carefully pivotally lowered to its inclined position where its lower 
extension element 29, FIG. 10, will solidly engage the adjacent end face 
of the outrigger beam. The jack cylinder 28a will remain stably in this 
position until again elevated. 
Thirdly, the cables 46 adjacent to jack cylinder 28a are disconnected from 
the outrigger assembly 24 while the downstream cables 46, FIG. 5, remain 
attached to the assembly. At this time, the crane superstructure can be 
operated in a sluing mode to slowly pull the assembly 24 laterally beneath 
the chassis frame 20 in one direction along the tracks 41. At the 
beginning of this pulling operation through the attached cables 46, the 
end of the assembly 24 having the dead rollers 44 thereon is lifted 
slightly so that the dead rollers can pass over the adjacent stop plates 
42. This being accomplished, the pulling continues and the live rollers 43 
will travel on the tracks 41 until they contact the downstream stop plates 
42, as shown in FIG. 6. During the movement of the outrigger assembly 
along the tracks 41, the inclined jack cylinder 28a is able to pass 
beneath the frame 20 without interference. 
Fourth and lastly in the method, the upstream lifting cables 46 are 
re-attached to the upstream connectors 45 of the assembly 24 and the 
assembly is carefully lifted off of the rails 41 and lowered to the ground 
or onto a supporting vehicle. 
In order to re-install the outrigger box or assembly, the above method 
steps are carried out in reverse order. The entire method is convenient, 
safe, expeditious and economical from a time and labor-saving standpoint. 
The necessity for removing one of the heavy jack cylinders or both 
cylinders is entirely eliminated. Only a very slight modifying of the 
chassis frame and outrigger assembly is required, as described, to achieve 
the objectives of the invention. 
The terms and expressions which have been employed herein are used as terms 
of description and not of limitation, and there is no intention, in the 
use of such terms and expressions, of excluding any equivalents of the 
features shown and described or portions thereof but it is recognized that 
various modifications are possible within the scope of the invention 
claimed.