AU600100B2 - Mobile crane - Google Patents

Description

Sj/ "ll NWEALTH OF AUSTRALIA TW OLLARS PATENTS ACT 1952-62 COMPLETE SPECIFICATION

(ORIGINAL)

FOR OFFICE USE: Application Number: Lodged: Class Int. Class Complete Specification Lodged: Accepted: Published: I his document contains the amendments made under Section 49 and is correct for printing.

FEE STAMP TO VALUE OF 1. 7. ATTACHED MAIL C^'jL^ Priority: Related Art: 0 f TO BE COMPLETED BY APPLICANT Name of Applicant: RAYDON AYERS LINES Address of Applicant: 2 Rasp Avenue, Medindie, State of South Australia, Commonwealth of Australia 0 Actual Inventor: RAYDON AYERS LINES Address for Service: R K Maddern Associates, 345 King William Street, Adelaide, State of South Australia, Commonwealth of Australia Complete Specification for the invention entitled: "MOBILE CRANE" The following statement is a full description of this invention, including the best method of performing it known to me.

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I. t This invention relates to a mobile crane of the type wherein a motor vehicle chassis provided with at least four wheels has a swivelling turret mounted rearwardly of its cab (but preferably close thereto), a jib on the turret which is rotatable through an angle exceeding 900°, outstanding jack arms which are retractable, and jacks on the respective jack arms.

0 0* BACKGROUND OF THE INVENTION 0 Mobile cranes of this type are in common use, and are very suitable for many purposes but are not suitable for use in confined areas since the jacks are usually carried on swivelling arms which are not adjustable for width.

:o :o One object of this invention is to provide means whereby extension of the jack arms is variable and can be selected to suit specific requirements.

BRIEF SUMMARY OF THE INVENTION i, In order to meet this object, the invention provides at least two jack arm assemblies carried side by side and extending across most of the width of the motor vehicle, each having a fixed frame with an intermediate extension arm and a primary extension arm, the primary extension arm being operatively coupled to the fixed frame by an hydraulic piston cylinder assembly, and an hydraulic jack carried by the outer end of the primary arm. A valve is used to control flow of oil to the piston -2cylinder assembly in such a way that the extension of the primary extension arm from the fixed frame is controlled. If the extension is only small, a latch between the primary extension arm and the intermediate arm will carry the intermediate arm out with it, so that the load imparted by the jack will be resisted by both the intermediate and primary arms.

0 More specifically, in this invention a mobile crane Scomprises at least two jack arm assemblies carried side o a :00 10 by side on a crane frame and extending across most of the o 000 width of a motor vehicle chassis, each jack arm assembly comprising a fixed frame, means securing the fixed frame 0 e to the chassis, an intermediate extension arm guided for o o movement by the fixed frame, a primary extension arm 0 00 0o 5 guided for movement by the intermediate extension arm, an 00,00 hydraulic piston/cylinder assembly operatively coupling the primary extension arm to the fixed frame, an hydraulic jack carried by the outer end of the primary arm, there o~r being valve means coupled to the piston/cylinder assembly operable to introduce pressure fluid thereto and control the extension of the primary extension arm from the fixed frame.

BRIEF DESCRIPTION OF THE DRAWINGS An embodiment of the invention is described hereunder in some detail with reference to and is illustrated in the accompanying drawings in which:- -3ti .i Fig. 1 illustrates a mobile crane which embodies the features of the invention; Fig. 2 is a longitudinal section showing a jack arm assembly and an hydraulic jack carried thereby; Fig. 3 is a section on line 3-3 of Fig. 2 and illustrating guide means between the piston/cylinder assembly and the primary extension arm; and Fig. 4 is a longitudinal section through the jib.

0 nIn this embodiment, a mobile crane 10 comprises 0 o 0 o10 a motor vehicle 11 which carries on it a crane frame o 04 "o o having a turret 12 (preferably as close as possible to the o.

cab 13). When the crane is in use, the jib 14 may be extended in two stages as illustrated in Fig. i, and the o vehicle 11 is stabilised by means of hydraulic jacks 15 of 0 0 5 which there are four. At least two of those four jacks are carried by jack arm assemblies 16 which lie side by side 0 4 on the crane frame but extend for most of the width of the vehicle 11.

Figs. 2 and 3 illustrate the jack arm assembly 16 and jacks 15 in some detail.

Each jack arm assembly 16 comprises an outer fixed frame 19 which is secured by means (not shown) to the crane frame on the chassis of the vehicle 11, an intermediate extension arm 20 and a primary extension arm 21. The frame 19 and the two arms are all of tubular cross-section shape as shown in Fig. 3, and slide with respect to one another. If required rub strips may be included to reduce friction.

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An hydraulic piston/cylinder assembly 23 is coupled at one end to the fixed frame 19 and at the other end to the primary extension arm 21 by respective coupling pins 24 and Since the hydraulic piston/cylinder assembly is very long, it is desirable to support it intermediate its ends, and use is made of a guide 26 on the piston OA 01rod end of the cylinder, the guide 26 engaging the inner o0 0 C. 0 surface of the primary extension arm 21. This inhibits 0 0 1* 0 any tendency for the piston/cylinder assembly 23 to 0 001) oo 0 a buckle when load is applied, although it would be 0 11 S appreciated by those skilled in the art that for support of jacks, the piston/cylinder assembly 23 normally 0 00 0 "operates under very low pressure.

If the jacks 15 are extended by the jack arm 0 assemblies 16 to extend out a long way from the vehicle, the primary extension arms 21 can be relatively small because the large mechanical advantage will have the effect of reducing the loading on the extended ends.

However this does not occur if because of insufficient access or other reasons, it is necessary to have the jacks relatively close to the vehicle. In order to provide additional support therefore to the relatively small primary extension arms, it is desirable that the intermediate extension arm 20 should also be extended, but under normal operating conditions this does not occur until such time as the primary extension arm 21 is first partly extended by the piston/cylinder assembly 23. To overcome this difficulty, use is made of a latch 28 having one portion on the extending end of the intermediate extension arm tube 20 and the other on the extending c;.d of the primary extension arm 21. This is shown only diagrammatically in Fig. 2, and the latch 28 may either be manually or automatically operated.

It is of course necessary to limit the movement of the intermediate extension arm 20 with respect to OqO00 the fixed frame 19, and also to rely upon stop means 0 l0 rather than full extension of the hydraulic piston/o o cylinder assembly 23 for extension of the primary extension arm 21. Use is therefore made of respective spring loaded stops 29 between these elements, which will inhibit oo excessive withdrawal.

o 00 ~0 5 Reference is now made to the jacks 15. Each jack comprises a jack ram 30. An outer rectangular guide tube o a 31 joins the jack ram 30 to the extending end of the primary extension arm 21, and the ram rod 32 of the jack 004 ram 30 is coupled at its lower end to an outer tubular jack column 33 which slides in guide tube 31. The jack column 33 is stiffened by stiffener plates 33a. The lower end of the ram rod 32 is connected to a foot mounting ball 34 as shown, and a foot 35 releasably engages that mounting ball and is retained thereto by a pair of tension springs 36 as shown in Fig. 2. The foot 35 can swivel about two axes so as to accommodate itself with respect to the supporting ground, and can be quickly and easily released or replaced by merely tensioning the springs 36 -6and removing from the lower end of the jack column 33.

Reference is now made to the jib 14.

Tfi) jib 14 is an extendible jib as is frequently used in cranes of the type being described. However it has provisions included which avoid the need for very heavy construction even though the jib may be used for lifting heavy weights.

Pin 38 mounts the jib for pivotal movement to the turret 12. As in the case of the jack arm assembly 16, the jib 14 comprises a plurality of rectangular tubes 4 one within the other. The outer tube 39 is the main load bearing member and is connected to the sleeve 40 which pivots about pin 38. Within the outer tube 39 is an inter- 4, mediate tube 41, and within that an inner tube 42. The !5 outer tube guides the intermediate tube which in turn guides the inner tube for extension movement.

A piston/cylinder assembly 43 within the inner tube operatively couples the outer and inner tubes 39 and 42 by means of coupling pins 44 and 45. The coupling pin 44 extends between sheet plates (not shown) and the coupling pin 45 between bridging plates 46 on the inner ii tube 42.

The piston/cylinder assembly 43 comprises an outer hydraulic cylinder 48 having a piston 49, the piston rod 50 of which is tubular and forms in the cylinder which contains a piston 51 and piston rod 52, the piston rod 52 terminating at its outer end in a mounting block -7- -a 0 0 4 a 0 0- 0 0000 0 o O 0 4 0 00© 0 O o 4o 4Y I 0 V 53 which carries the mounting pin 45. Mounting block 53 contains a valve 54 which controls the extension of the inner piston rod 52, the valve 54 being a pilot operated check valve arranged so that when the piston rod 52 is extended to a selected length, the valve can be shut off and an hydraulic lock prevents moving parts from operating in the case of the inner cylinder, any operation thereafter being effected solely by the outer hydraulic cylinder 49 and its piston rod 504 This contributes 10 considerably to reduction in weight.

Reduction in weight however is also assisted by the guide means of the jib assembly. The intermediate tube 41 carries on its axially inner end a guide 57 provided with a bronze wear strip 58 which slides over the outer surface of the outer hydraulic cylinder 48.

This guide is itself coupled to a plate 59 secured to the axially outer end of the inner cylinder (tubular piston rod 50) by an octagonal connecting tube 60. The plates 59 also bear against the inner surface of the inner tube 42.

Reference is now made to further features of the invention: For maintenance purposes it is desirable to readily withdraw the ram assemblies from the sockets of the jack arm, and to achieve thisr coupling pin 24 is an elongate pin which extends through the mounting end of the inner (primary) tube 21 of each jack arm, and by simply withdrawing the pin the entire assembly can be withdrawn 4 -8in an endwise direction. This facility is also useful for assembly of hydraulic hoses (not shown).

In some embodiments of the invention, the outer end of the ram is provided with a large guide which slides within the inner jack arm member to ensure that the ram is supported in a central position, although this feature exists in prior art.

The oil supply to the small extension piston/cylinder ,i of the jib 14 is achieved by means of a hose reel mounted S 10 near the inner end of the outer tube (for example, on the turret), with hoses, and sometimes electrical cables, extending to the outer end of the small extension ram, where they are connected to conduits within its piston 4 j rod. This oil supply can be used to operate other i 4'15 attachments at the outer end of the jib assembly by means of solenoid operated valves.

In order to avoid any difficulty of the small piston/cylinder working under load conditions, the rams are provided with individual solenoid valves, all of which are mounted on or near the mounting block 53. This greatly simplifies the pipework.

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Claims (12)

1. A mobile crane comprising at least two jack arm assemblies carried side by side on a crane vehicle chassis and extending in opposite directions across most of the width of a motor vehicle chassis, each jack arm assembly comprising a fixed frame, means securing the fixed frame to the chassis, an intermediate extension arm guided for movement by the fixed frame, a primary extension arm guided for movement by the intermediate extension arm, an hydraulic piston/cylinder assembly operatively coupling the primary extension arm to the fixed frame, a guide carried on an end of the cylinder of each piston/ o o cylinder assembly engaging a said primary extension arm in such o a way as to support the piston/cylinder assembly intermediate its ends during movement of the primary extension arm, 0 o 0 an hydraulic jack carried by the outer end of the primary 000 4 f 0 4 arm, there being valve means coupled to the piston/cylinder assembly operable to introduce pressure fluid thereto and control the extension of the primary extension arm from the fixed frame.

2. A mobile crane assembly according to claim 1 wherein 11Z' said fixed frame is an outer tube, said intermediate arm is an intermediate tube slidable within the outer tube, said primary extension arm is an inner tube slidable within the intermediate tube, and said hydraulic piston/cylinder assembly extends into, and is coupled to, said inner tube. ~,VT 0~ I1Rci

3. A mobile crane assembly according to claim 2 wherein said guide is slidably engaged by the inner surface of said inner tube.

4. A mobile crane assembly according to claim 2 or claim 3 further comprising a latch having one latch portion on the extending end of the inner tube releasably engaging another latch portion on the extending end of the intermediate tube and operable to extend the intermediate tube along with the inner tube during initial expansion of the piston/cylinder assembly.

A mobile crane assembly according to any one of claims 2 to 4 wherein said jack comprises a jack ram, guide means joining the cylinder of the jack ram to the extending end of the inner tube, and a tubular jack column surrounding the jack ram and coupled to the moving end of the rod of the jack ram.

6. A mobile crane assembly according to claim 5 further comprising a ball projecting from the lower end of said ram rod, a foot releasably engaging the ball for swivelling movement with respect thereto, and springs coupling the foot to the lower end of the tubular jack column.

7. A mobile crane assembly according to any preceding claim further comprising an extendable jib having an outer tube, a mounting pin carried at one end of the outer tube, an intermediate tube guided for movement by the outer tube, an inner tube guided for movement by the intermediate tube, a piston/cylinder assembly within the inner tube operatively coupling the inner and outer tube, and valve means on the extending end of the piston/cylinder assembly controlling flow of pressure fluid thereto. -11- m m 0

8. A mobile crane assembly according to claim 7 wherein said piston/cylinder assembly of the jib comprises a pair of concentric hydraulic cylinders each containing a piston and each piston having a piston rod, the outer piston rod being tubular and comprising the inner cylinder, and means securing an end of the outer piston rod and further means securing an end of the inner piston rod respectively to said outer and inner cylinders.

9. A mobile crane assembly according to claim 8 wherein said valve means are operative to close access of oil to the inner cylinder when the piston rod thereof is extended, so as to produce an hydraulic lock.

A mobile crane assembly according to claim 8 or claim 9 further comprising a guide on the axially inner end of the intermediate tube slidably engaging the outer surface of the outer cylinder.

11. A mobile crane assembly according to c',aim 10 further comprising a plate on the axially outer end of the inner cylinder, and a connecting tube surrounding the outer cylinder and joined at its respective ends to that said plate and said guide.

12. A mobile crane assembly substantially as hereinbefore described with reference to and as illustrated in the accompanyi.'.g drawings. Dated this llth day of May, 1990. RAYDON AYERS LINES, By his Patent Attorneys, R.K. MADDERN ASSOCIATES -12- SNT0