Removable live mast and hoist unit

A removable live mast and hoist unit is disclosed for use with a crane of the type having a pivotal live mast releasably connected to the boom of a crane for raising and lowering the boom. The unit includes the live mast and a boom hoist frame that are rigidly secured together with the boom hoist, reeving, mast bridle and bail all partially enclosed within portions of the mast and a cavity in the frame to protect the reeving and to permit easy removal of the unit without unwinding the reeving.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to crane assembly and disassembly procedures 
and more particularly relates to an apparatus for rigidly securing a live 
mast, boom hoist frame, and drums with reeving together as a unit for 
quick attachment and removal from a crane. 
2. Description of the Prior Art 
It is well known that large cranes or the like must be disassembled and 
reassembled so as to be moved by trucks or trains between different work 
sites spaced considerable distances apart. One type of crane uses a live 
mast with a boom hoist connected to the mast by multiple strand reeving 
for pivotally raising or lowering the boom through fixed pendant lines. 
Heretofore, one problem for assembling or disassembling this type of crane 
was that the reeving had to be wound on and off of the associated drum for 
each long move of the crane, which winding process is both time consuming 
and requires considerable effort. 
In another type of crane the boom is pivotally raised and lowered by a 
winch on the upper works and reeving connected thereto and between sheaves 
on a gantry frame and sheaves on a bridle frame. Pendants connect the 
bridle frame to the boom. When the crane is in operation, the gantry is in 
rigid fixed position; however, the gantry may be collapsed so that the 
gantry, boom hoist, and reeving may be removed as a unit. U.S. Helm et al 
Pat. No. 3,977,530 discloses such a structure. 
SUMMARY OF THE INVENTION 
In accordance with the present invention a boom hoist frame, carrying a 
power driven boom hoist and a pivotal bail assembly is removably mounted 
on the upper works of a crane. Bridle sheaves on a live mast are connected 
to the bail and winch by the reeving. During normal crane operation the 
live mast is connected to a boom by pendant lines and is pivoted in a 
vertical plane for raising and lowering the boom in response to rotation 
of the winch drum. When the crane is to be disassembled, the live mast is 
disconnected from the boom and is lowered to a horizontal position with 
portions of the live mast in nested position within the boom hoist frame. 
Portions of the bail, and hoist are partially encompassed with the live 
mast and frame to protect these components during shipping. The live mast 
is rigidly secured in nested position to the frame, and the live mast and 
frame are disconnected and removed from the upper works as a unit with the 
reeving connected and with the mounting holes in the live mast and frame 
locked in fixed position relative to each other for easy reassembling.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
The removable live mast and hoist unit 10 (FIGS. 3 and 4) of the present 
invention is shown in operative position on a crane 12 in FIGS. 1 and 2. 
The crane 12 comprises a lower works 14 supported on track assemblies 16. 
An upper works 18 is supported for rotation about a vertical axis on the 
lower works 14 and includes an operator's cab 20 at its front end, one or 
more load winches 22, and power means including an engine 23 for driving 
the track assemblies, the load winches 22 and a boom hoist winch 26. A 
boom 28 is pivotally supported near the front end of the upper works 18 
and is prevented from excessive rearward pivotal movement by telescopic 
boom stops 30 that are pivotally connected between the boom 28 and the 
upper works 18. The forward end of a live mast 32 is generally U-shaped 
and includes two legs 33 with their forward ends pivotally connected to 
forward ends of the upper works 18 by removable pivot pins 34. Transverse 
members 35 are rigidly secured to the legs 33 to stiffen the live mast. 
The rear end of the live mast 32 is connected to the upper end of the boom 
28 by fixed length pendants 36, and a multi-sheave bridle frame 38 is 
journaled on the rear end of the mast 32. 
A boom hoist and counterweight frame 40 is connected to the rear end of the 
upper works 18 by four removable pins 42 (only two shown in FIG. 4) which 
are received within cooperating ears 44 and 46 rigidly secured to the 
upper works 18 and to the frame 40, respectively. The frame 40 releasably 
supports three counterweights 48 secured therebelow during operation of 
the crane, but released therefrom when the live mast 32 and frame 40 of 
the hoist unit 10 are to be removed as a unit from the crane. 
The boom hoist frame 40 is of generally U-shaped construction and includes 
a base 50 (FIGS. 2 and 3) and upstanding walls 52 having means defining 
angle cut-outs 54 for receiving portions of the live mast legs 33 in 
nesting engagement when in their transport position as shown in FIGS. 3 
and 4. The boom hoist 26 with its two section drum 57 is housed within the 
U-shaped frame 40. Also, arms 58 of a bail assembly 60 are pivoted by pins 
62 to the inner walls 52 of the frame 40, which walls are also grooved at 
66 to permit the arms 58 to pivot from their operative upright positions 
(FIGS. 1 and 2) to their stowed positions (FIGS. 3 and 4). A bail 68 is 
journaled on the arms 58, and a pair of guide sheaves 70 are rotatably and 
transversely slidably received on a shaft secured to the arms 58 to guide 
the end strands of the reeving when being wound on or off the drum 57 of 
the boom hoist winch 26. When the bail assembly 60 and components thereon 
are in their stowed position, they are partially nested within and 
protected by the U-shaped hoist frame 40 and the adjacent members of the 
live mast 32. Also, when stowed, the arms 58 are connected to the frame 40 
by tubular struts 71 bolted to the bail arms 58 and to the frame 40 for 
preventing pivotal movement of the bail assembly when being lifted from 
the crane by an auxiliary crane (not shown) and harness H connected to the 
frame 40 and bail arms 58 as shown in dotted lines in FIG. 4. 
The two section drum 57 of boom hoist 26 receives the end portions of the 
reeving 72, which reeving is trained around the live mast bridle 38, the 
bail 68, and the guide sheaves 70 before being wound on the associated 
sections of the hoist drum 57. Thus, when the boom hoist 26 is selectively 
operated to rotate the drum 57 in one direction, the live mast 32 will 
pivot clockwise (FIG. 1) thereby raising the boom 28; and when rotated in 
the opposite direction the live mast 32 will pivot counterclockwise 
thereby lowering the boom. 
In the disassembly operation, the boom 28 is first pivotally lowered from 
an active position such as illustrated in FIG. 1 until the booms outer 
ends rest on the ground. During this movement the boom hoist 26 controls 
counterclockwise movement of the live mast 32. The pendant lines 36 are 
then disconnected from the outer end of the live mast 32, and the live 
mast is connected to the load line of an auxiliary crane (not shown) to 
resist free clockwise gravitational movement of the mast 32 and to 
maintain tension on the reeving 72 as the boom hoist 26 reeves in the 
line. As the live mast 32 approaches the stored or transport position 
shown in FIGS. 3 and 4, the bail assembly 60 pivots from an exposed 
position as shown in FIG. 1 to its stowed position as shown in FIGS. 3 and 
4. The straps 71 are then bolted in position so that the reeving 72, hoist 
26, bail 68 and live mast bridle 38 are substantially confined within 
walls defined by the U-shaped boom hoist frame 40 and the outer end 
portions of the live mast. Thus, the reeving is wound and held under 
tension on its several supporting members when in stowed position thereby 
eliminating the need for unwinding and rewinding the reeving when the live 
mast is again to be placed in an operative position. The live mast 32 is 
then firmly locked to the boom hoist frame while nested in the cut-outs 54 
by means such as bolts 74 and straps 76 which are provided to rigidly 
secure the live mast 32 to the frame 40 prior to releasing the pins 34 and 
42. 
When the live mast 32 has been lowered into its lowermost position with the 
mast legs 33 nested in the cutouts 54 of the frame 40, the forward portion 
of the legs 33 are connected to the upper works by the removable pins 34. 
The lock means 74,76 retain the pin positions for fast and easy 
reassembly. Thus, when the live mast has been fully lowered and secured to 
the frame 40, the two live mast pivot pins 34 and the four hoist frame 
pins 42 are accurately positioned relative to each other. 
After the live mast 32 and boom hoist frame 40 have been locked together as 
a unit and after the counterweights 48 have been removed, the unit 10 is 
connected to an auxiliary crane (not shown). The mast connecting pins 34 
and the frame connecting pins 42 are then removed and the auxiliary crane 
(not shown) is actuated to lift the harness H and the removable live mast 
and hoist unit 10 free of the crane 12 for storage or trucking to a new 
location. 
When it is desired to reassemble the unit 10 on the upper works 18, the 
auxiliary crane (not shown) is used to place the lower end of the live 
mast 32 and the ears 46 on the frame 40 in position to receive the 
associated locking pins 34 and 42 on the upper works 18. The pins 34 and 
42 are then inserted, winch control and power means are reconnected, and 
the mast 32 is unlocked from the frame 40. The auxiliary crane is then 
attached to the outer end of the live mast 32 to pivot the outer end of 
the live mast 32 counterclockwise while the winch is driven but retains 
tension on the reeving 72. The pendant lines 36 are then reconnected to 
the live mast 32 thus completing the reassembly operation. 
From the foregoing description it is apparent that the removable live mast 
and hoist unit of the present invention locks a portion of the live mast 
in nesting position with the boom hoist frame when in stowed position for 
substantially confining the winch, bail and winch drum with the reeving 
attached within protective walls of the live mast and winch frame. Also, 
accurate locking of the nested live mast to the frame provides for easy 
reconnection of the unit to the frame. 
Although the best mode contemplated for carrying out the present invention 
has been herein shown and described, it will be apparent that modification 
and variation may be made without departing from what is regarded to be 
the subject matter of the invention.