NZ506169A - Hydraulic drop hammer with friction rollers to lift hammer and movable to allow hammer to fall - Google Patents

Abstract

Hammer member 3 slides in guide 1 and is raised by hydraulically driven friction wheels 9. Member 3 is lifted by wheels 9 being pressed against faces of member 3 by pivoted arms 11 and compression springs 15. Member 3 is dropped by hydraulic actuator 14 acting through pivoted arms to compress springs 15 and disengage friction wheels 9.

Description

50 6 J 69 Patents Form No. 5 Our Ref: JT214035 Patents Act 1953 COMPLETE SPECIFICATION HYDRAULIC DROP HAMMER We, AUSMOSE PTY LIMITED, an Australian Company of 11 Hilly Street, Mortlake, New South Wales 2137, Australia hereby declare the invention, for which we pray that a patent may be granted to us and the method by which it is to be performed, to be particularly described in and by the following statement: PT05A19311 Intellectual Property Office of NZ -7 This invention relates to an hydraulic drop hammer and has been devised particularly though not solely for driving metal post reinforcing members into the ground.

It is well known to provide drop hammers in various different configurations, 5 adapted for many uses including 'pile driving' and the driving of posts into the ground for different applications Such posts might typically be in timber or comprise a metal post of any section which may be formed in steel plate which may be used for many different applications. One such application is the driving of reinforcing metal posts into the ground adjacent timber poles such as power poles or telegraph poles, which have 10 become weakened in the groundline area with time, for example by rot or insect attack.

In such situations, it is known to provide a drop hammer which can be positioned alongside the pole and used to drive a reinforcing post a considerable distance into the ground alongside the pole, which is then banded or otherwise secured to the post for reinforcement of the pole.

In the past, some drop hammers of this type have typically been provided with an elongate guide channel and an elongate weighted hammer member arranged to slide within the channel so that the head of the hammer may impact on the top of a post being driven into the ground, when the hammer member is raised to an elevated position and then released to fall under its own weight. The raising mechanism in known drop 20 hammers of this type is typically driven from the PTO (power take off) of a tractor or a single motor onto drive pulleys on the drop hammer where the driving force is transmitted via a pair of drive belts to a pair of friction rollers which are engagable with the sides of the weighted hammer member to raise the hammer member to its elevated position when driven upwardly by the friction rollers.

Such prior art mechanisms have the disadvantages that the belt drive arrangement is cumbersome and prone to problems in use, particularly as one of the belts is typically twisted m order to achieve a counter-rotating drive between the two friction rollers, and a mechanical lever system is also required to engage and disengage the friction rollers 5 The present invention therefore, provides an hydraulic drop hammer including an elongate hammer guide, an elongate weighted hammer member arranged to slide within the guide so as to be able to fall under its own weight when released from an elevated position with the guide positioned substantially vertically, a pair of tracks arranged on opposed faces of the hammer member, a pair of friction wheels mounted on the guide 10 and engagable with the tracks, one to each, at least one hydraulic drive motor adjacent and coupled to at least one said friction wheel to rotate that friction wheel on actuation of the motor, and a clamping mechanism arranged to move the friction wheels into and out of engagement with the tracks, arranged such that when the motor is actuated and the friction wheels engaged with the tracks, the hammer member is raised to the elevated 15 position, whereupon the clamping mechanism may be disengaged allowing the hammer member to fall under its own weight.

Preferably, two said drive motors are provided, one coupled directly to each friction wheel, said drive motors being arranged to rotate in opposite directions.

Preferably, said clamping mechanism includes a pair of lever arms pivotally mounted to said guide with said friction wheels rotatably mounted thereon.

Preferably said lever arms are pivoted by springs arranged to move the friction wheels into engagement with the tracks on the hammer member.

Preferably, the springs are counteracted by a linear actuator arranged to apply a force between the lever arms, moving the friction wheels out of engagement with the tracks.

Preferably, the linear actuator includes an hydraulic piston and cylinder assembly.

Preferably, said lever arms are pivotally mounted to said guide at an intermediate point on said lever arms, the drive motors and friction wheels being supported at one end of the lever arms, and the linear actuator connected between the other ends of the lever arms.

Preferably, the linear actuator includes an hydraulic piston and cylinder assembly ] 0 arranged to float relative to the remainder of the linear actuator.

Notwithstanding any other forms that may fall within its scope, one preferred form of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Fig. 1 is a diagrammatic side view of a drop hammer of the type according to the 15 invention showing the hammer member in its lower position in Fig. 1 A, and a fully elevated position in Fig IB Fig 2 is a diagrammatic rear view of an hydraulic drop hammer according to the invention; Fig. 3 is a diagrammatic front view of the drop hammer shown in Fig. 2; and 20 Fig. 4 is a diagrammatic plan view to an enlarged scale of the clamping mechanism including the linear actuator and springs used in the drop hammer shown in Figs. 2 and 3 The hydraulic drop hammer has an elongate hammer guide 1 which is typically in the form of a metal C-section having an open rear face 2.

Slidably mounted within the guide 1 is an elongate weighted hammer member 3, typically extending from a lower end 4 to an upper end 5 and having a hammer head portion 6 protruding outwardly through the open face of the guide 1 incorporating a striking face 7.

The hammer member has a considerable weight due to the mass contained not only within the protruding head portion 6 but also within the entire length of the hammer member from the top 5 to the bottom 4, which may typically comprise solid steel posts or beams.

In use, the hammer member is raised from a position shown in Fig. 1A to an 10 elevated position which may be as high as the fully elevated position shown in Fig. IB by the mechanism described below, whereupon it can be released to fall under its own weight with the striking face 7 arranged to impact on the top 23 of a post 24 to be driven into the ground surface. The post 24 shown as an example only, is a dished sheet metal post adapted to be driven into the ground to reinforce an adjacent pole 25, typically a 15 telegraph or power pole To assist in locating the apparatus, straps or chains 26 are provided to wrap around the pole, and a support member 27 is pivotally mounted at 28 to the base of the guide 1, adjustable by mechanism 29 The hammer member 3 may have tracks consisting of simple plane surfaces 8 on opposed faces which engage with a pair of friction wheels 9 mounted on the guide 1 so 20 that the friction wheels bear against the tracks on the sides of the hammer member which can be driven upwardly by counter rotation of the friction wheels in the appropriate direction.

Each friction wheel is directly coupled to and driven by an hydraulic motor 10 which is in turn mounted on the upper end of a lever arm 11 pivotally connected to the guide 1 by way of pivot pins 12 at either end of a cross member 13 The lever arms 11 which may typically be of channel section as shown in Fig. 4 5 are forced apart at their lower ends by way of compression springs 15 acting between the lower ends of lever arms 11 and the adjacent portions of C-section guide 1 so as to provide a clamping force between the upper ends of the lever arms 11 forcing the friction wheels 9 into engagement with the tracks 8 The springs 15 of the clamping mechanism are mounted with tension adjustment screws (not shown), between the lever arms 11 and 10 the guide 1.

The springs are compressable to disengage the friction wheels 9 from the tracks 8, by a linear actuator 14 typically including a cross tie 16 mounted on the guide 1 (Fig 4) and having pivot pms 17 at each end on which are pivotally mounted toggle arms 18 One end of each toggle arm is connected by way of pivot pins 19 to lever arms 11. 15 The other ends of the toggle arms 18 are interconnected between pivot points 21 by way of an hydraulic piston and cylinder assembly 22.

Hydraulic pressure is supplied to the piston and cylinder assembly 22 by hydraulic hoses 30 from control valves 31 mounted on plate 32. Also mounted on the plate 32 are control valves for the hydraulic motors 10 connected by hydraulic hoses 33. The control 20 valves are operated by levers 34.

For the convenience of the operator, plate 32 with attached control valves and levers can be rotated about a vertical axis formed by pins 35, controlled by a loop handle 36 which also serves to guard the levers 34 from accidental knocking.

When it is desired to operate the linear actuator to disengage the friction wheels 9 from the tracks 8, the piston and cylinder assembly 22 is expanded by the application of appropriate hydraulic pressure, causing the toggle arms 18 to move together at their upper ends (as shown in Fig. 4) 19, compressing the compression springs 15 and causing 5 the lower ends of the lever arms 11 to move toward one another, and the hydraulic motors 10 and friction wheels 9 to move apart and disengage from the tracks 8.

It is desirable that the hydraulic piston and cylinder assembly 22 'float' relative to the remainder of the linear actuator 14, le to not be attached other than by way of the toggle arms 18, so that the retraction forces are equalised between the two wheels The 10 equilibrium position of the lever arms 11 and the pressure exerted by the friction wheels 9, can then be adjusted by nuts 37 on threaded rods 38.

In use, hydraulic pressure is applied to the two hydraulic drive motors 10 via the control valves and tubing 33, causing the two motors to counter-rotate and drive hammer member 3 upwardly by the friction drive between the wheels 9 and the tracks 8. When 15 the hammer member has reached an elevated position, the linear actuator 14 is operated by applying hydraulic pressure to the piston and cylinder assembly 22 causing the friction drive wheels 9 to move apart and be disengaged as described above, and allowing the hammer member to fall under its own weight until the strike face 7 impacts on the top of the post 27 or other member to be driven.

It is a particular advantage of the hydraulic drop hammer according to the invention that the mechanism is extremely compact and simple, and able to be made of robust components, leading to long life and reliability in the field. Furthermore, the entire power supply needed to drive both the hydraulic motors 10 and the linear actuator 14 can be provided from a single hydraulic pump which is typically a standard truck hydraulic power take-off unit connectable to the control valves 31 by way of simple flexible hydraulic hoses (not shown)

Claims (1)

1. -9- THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS.- 1 An hydraulic drop hammer including an elongate hammer guide, an elongate weighted hammer member arranged to slide within the guide so as to be able to fall 5 under its own weight when released from an elevated position with the guide positioned substantially vertically, a pair of tracks arranged on opposed faces of the hammer member, a pair of friction wheels mounted on the guide and engagable with the tracks, one to each, at least one hydraulic drive motor adjacent and coupled to at least one said friction wheel to rotate that friction wheel on actuation of the motor, and a clamping 10 mechanism arranged to move the friction wheels into and out of engagement with the tracks, arranged such that when the motor is actuated and the friction wheels engaged with the tracks, the hammer member is raised to the elevated position, whereupon the clamping mechanism may be disengaged allowing the hammer member to fall under its own weight. 15 2 An hydraulic drop hammer as claimed in claim 1 wherein a pair of said drive motors are provided, adjacent and coupled to each respective one of said pair of friction wheels. 3 An hydraulic drop hammer as claimed in claim 2 wherein said drive motors are arranged to rotate in opposite directions and are directly coupled to their respective 20 friction wheels. 4. An hydraulic drop hammer as claimed in any one of the preceding claims wherein said clamping mechanism includes a pair of lever arms pivotally mounted to said guide with said friction wheels rotatably mounted thereon, one to each. - 10- 5 An hydraulic drop hammer as claimed in claim 4 wherein said lever arms are pivoted by springs arranged to move the friction wheels into engagement with the tracks on the hammer member. 6 An hydraulic drop hammer as claimed in claim 5 wherein the springs are 5 counteracted by a linear actuator operable to apply a force between the lever arms, moving the friction wheels out of engagement with the tracks. 7 An hydraulic drop hammer as claimed m claim 6 wherein the linear actuator includes an hydraulic piston and cylinder assembly. 8 An hydraulic drop hammer as claimed in either claim 6 or claim 7 wherein said 10 lever arms are pivotally mounted to said guide at an intermediate point on said lever arms, the drive motors and friction wheels being supported adjacent one end of the lever arms, and the linear actuator connected between the other ends of the lever arms. 9. An hydraulic drop hammer as claimed in claim 8 wherein the hydraulic piston and cylinder assembly is arranged to float relative to the remainder of the linear actuator 15 10. An hydraulic drop hammer when constructed arranged and operable substantially as described herein with reference to the accompanying drawings. Au^ose Ft/Limited By It 3 Attorneys Balchim Shels :on/Waters intellectual Property Office of NZ - 7 AUG 2000