GB2053147A - Travelling attachment for ring supported lift crane - Google Patents

Abstract

A travelling attachment (45) including a pair of crawler assemblies (46, 47) and frame elements (48, 51, 52) is provided for interconnection to the ring (15) of a ring supported crane (10) so the crane can travel under load. The crawler assemblies (46, 47) are shown pivotally mounted to reinforced end portions (53, 54) of the frame (48) by yoke elements (55, 56) and vertical pivot posts (57, 58) and provided with hydraulic cylinders (61, 62) interconnecting the frame end portions (53, 54) and the crawler assemblies (46, 47) to permit turning the assemblies and facilitate moving the crane under load about a curved path. The crawlers (46, 47) may be selectively and reversibly powered by means of hydraulic motors (65, 66). <IMAGE>

Description

SPECIFICATION Travelling attachment for ring supported lift crane This invention relates generally to lift cranes and more particularly concerns a travelling attachment for ring supported cranes.

In response to ever-increasing user needs, aelf- propelled cranes have been made capable of lifting ever greater loads. While a number of factors enter into determining crane capacity, a basic limitation arises from the fact that, inevitably, the weight of the crane and its load must be transferred to the earth.in some stable fashion, and, if rotation of the load is desired, the crane-earth connection must be made stable through the arc of crane rotation.

A significant increase in crane capacity was achieved by providing a self-propelled crane with the support ring and extended boom carrier disclosed in U.S. Patent Nos. 3,485,383 and 3,878,944.

In this design, the weight of the crane and its load is transferred to the ground through a large diameter, track-like ring. As shown in these patents, and as practiced commercially for some years, the support ring is either blocked into place by timbers fitted and wedged beneath and completely around the ring or is supported by a plurality of jacks spaced around the periphery of the ring.

According to the present invention there is provided a crane having an upper structure pivoted on a lower car body including means for moving the crane over the ground with a pair of support beams secured to and forming a part of the lower car body, a track-like ring secured to the beams and horizontally surrounding the lower car body, a boom carrier pivoted for vertical movement on the upper structure and riding for rotation on the ring, a boom mounted on the boom carrier for lifting a load, a counterweight carrier pivoted for vertical movement on the upper structure and riding for rotation on the ring, means interconnecting the counterweight carrier and the boom, and characterised by a travelling support attachment including a pair of laterally spaced crawler assemblies respectively located adjacent one end of the pair of beams and means including a plurality of frame elements interconnecting the crawler assemblies and for supporting the ring between the support beams to permit movement of the crane and ring over the ground while the boom is lifting a load.

The invention will now be described by way of example only with particular reference to the accompanying drawings wherein: Figure 1 is a fragmentary elevation of a crane support structure embodying the present invention and Figure 2 is a section taken approximately along the line 2-2 in Figure 1.

A crane 10 is shown, having an upper structure 11 mounted for rotation on a car body 12 through a roller path 13. The crane 10 is normally mobile and, for moving over the ground, crawler assemblies 14 form part of the car body 12.

In order to increase the capacity of the crane 10, a track-like ring 15 is secured to the ends of support beams 16 and 17 so as to horizontally surround the car body 12. Preferably, the ring has an I-beam cross section with a hardened upper path surface. To adapt the crane for this ring support configuration, the support beams 16, 17 are secured to the car body 12 running outboard and parallel to the crawler assemblies 14 so that the beams become part of the car body.

The geometry of the crane 10 contributes to its high capacities when used with the ring support. A boom carrier 25 is pivoted for vertical movement on the upper structure 11 and provided with a roller assembly 26 for rotation on the ring 15. A boom 27 is mounted on the carrier at what becomes the load lifting fulcrum 28 of the system, and a load lift lin 29 runs along and over the end of the boom 27. A counterweight carrier 31 is also pivoted for vertical movement at 32 on the upper structure 11 and the carrier extends the opposite direction from the boom carrier 25 to ride on the ring 15 through roller assemblies 33, only one of which is shown. Courterweights 34 are stacked on the carrier 31.

In effect, all structure to the non-boom side of the fulcrum 28 is available for counterbalancing and stabilising the crane 10. Preferably, a mast 36 is mounted on the carrier 25 and boom lift rigging 37 interconnects the tops of the mast 36 and the boom 27 for moving the boom vertically. The mast 36 is secured by pendants 38 to gantry structure 39 on the upper structure 11 to form a substantially rigid assembly, and other pendants 41 provide substantially rigid connections between the counterweight carrier 31 and the top of the mast 36. Struts 42 establish the substantially fixed angular position to the mast 36. This geometry creates a stable, high capacity crane.

Atravelling support attachment 45 is provided for supporting the ring 15 under the fulcrum 28 to permit movement of the crane 10 and ring 15 over the ground while the boom 27 is lifting a heavy load.

In the preferred embodiment the travelling support attachment 45 includes a pair of laterally spaced crawler assemblies 46 and 47 respectively located adjacent the forward ends of the support beams 16 and 17. The crawler assemblies 46,47 are connected together by a frame element 48 which, in turn, is interconnected from adjacent its ends to the car body 12 by a pair of frame elements 51 and 52 on which the ring 15 is supported. Preferably, the frame elements 51,52 are pin connected to the car body 12 and project forwardly in diverging relation between the lateral support beams 16, 17 where they are connected to the frame element 48.

When a heavy load is lifted by the boom 27, the forces are transmitted down through the boom 27 and mast 36 to the boom carrier 25 riding on the ring 15 adjacent the fulcrum 28. The lifting forces are also transmitted through pendants 41 to the counterweights 34 stacked on the carrier 31 tending to lift the carrier 31 off the ring 15. Since the attachment frame elements 51,52 support the ring 15 adjacent the fulcrum 28, the lifting forces pass primarily down through the ring 15 to the attachment assembly and are resisted by the crawler assemblies 46,47 engaging the ground. If it is desired to travel with a load, power may be applied to the main crawler assemblies 14 and the crane 10 and ring 15 may be "walked" ahead with the load being primarily supported by the travelling support attachment 45 and its crawler assemblies 46,47.Of course, the crane 10 may also be travelled rearwardly under load by reversing the direction of movement of the main crawlers 14.

The crawler assemblies 46,47 are preferably pivotally mounted to reinforced end portions 53, 54 of the frame 48 by yoke elements 55 and 56 and vertical pivot posts 57 and 58, respectively. Additionally, hydraulic cylinders 61 and 62 are provided interconnecting the frame end portions 53, 54 and the crawler assemblies 46,47 to permit turning the crawler assemblies 46,47 and thus facilitate mpving the crane 10 under load about a curved path.

While the crawler assemblies 45,46 need not be independently powered for most applications, the mobility and maneuverability of the crane 10 travelling under load may be further enhanced by selectively and reversibly powering the crawlers 45,46 such as by independent hydraulic motors 65 and 66, respectively. Operation of these motors 65,66 not only increases the traction power of the crane 10, since the load is primarily supported on the crawlers 45,46, but also, ensures more positive steering control when the crane is moved in a curved path.

The counterweight carrier 31 may be provided with wheeled support means 67 to resist rearward tipping of the crane 10 and ring 15 when a heavy load is not being supported by the boom 27. This avoids the necessity of removing portions of the counterweight 34 from the carrier between successive heavy lift operations. Preferably, the wheeled support means 67 are pivotally mounted to the counterweight carrier about substantially vertical axes such as pivot posts 68 so that the wheels may caster as the crane 10 turns either during swinging or travelling movement.

It should also be appreciated that the travelling support attachment 45 and/or the wheeled support means 67 may be quickly and conveniently attached and detached from a standard ring supported crane such as disclosed in U.S. Patent No. 3,878,944 which is incorporated herein by reference. As shown in that patent, a plurality of ring support arms 71 are pivoted for vertical movement on the car body 12 and extend outwardly to underlie the ring 15 at spaced points around the ring periphery. A plurality of jacks 72 are positioned one at the end of each of the arms 71 with the jacks 72 being sized so as to engage the ground when extended and lift the ring 15, the car body 12 and the crawler assemblies 14 from the ground.

To facilitate setting up the ring 15, hydraulic jacks 73 are mounted at the four ends of the support beams 16,17. Manipulation of these jacks 73 allows the ring 15 to be lifted and levelled, whereupon the manual jacks 72 can be quickly extended to provide firm supportforthe ring completely around its periphery and to facilitate coupling and uncoupling the travelling support attachment 45 andlor the wheeled support means 67.

Claims (6)

1. -1. - Acrane having an upper structure pivoted on a lower car body including means for moving the crane over the ground with a pair of support beams secured to and forming a part of said lower car body, a track-like ring secured to said beams and horizon tally surrounding said lower car body, a boom carrier pivoted for vertical movement on said upper structure and riding for rotation on said ring, a boom mounted on said boom carrier for lifting a load, a counterweight carrier pivoted for vertical movement on said upper structure and riding for rotation on said ring, means interconnecting said counterweight .carrier and said boom, and a travelling support attachment including a pair of laterally spaced cra.wler assemblies respectively located adjacent one end of said pair of beams and means including a plurality of frame elements interconnecting said crawler assemblies and for supporting said ring between said support beams to permit movement of said crane and ring over the ground while said boom is lifting a load.
2. 2. A crane as claimed in Claim 1 wherein said crawler assemblies are connected to said frame elements through vertical pivot posts and means are provided for pivoting said crawler assemblies about the axes of said posts.
3. 3. A crane as claimed in Claim 1 wherein said crawler assemblies each include an endless track and hydraulic motor means provided for selectively and reversibly driving said tracks.
4. 4. A crane as claimed in Claim 1 wherein said counterweightextends.outboard of said ring and wheeled support means are provided under said counterweight carrier outboard of said ring.
5. 5. A crane as claimed in Claim 1 wherein said wheeled support means are pivotally mounted to said counterweight carrier about substantially vertical axes.
6. 6. A crane substantially as hereinbefore described and as shown in the accompanying drawings.