GB2029797A

GB2029797A - Tree Felling Jack

Info

Publication number: GB2029797A
Application number: GB7921866A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1978-09-15
Filing date: 1979-06-22
Publication date: 1980-03-26

Abstract

A manually operated jack for use in tree felling comprises an elongated manually operable lever 1 having in the region of one end a foot 2, a pressure plate 3 hinged 13 to said foot and a pressure element 4 connected in spaced relation to said pressure plate 3 and foot 2 by two links 5, 6 pivotally interconnected with said pressure element 4 at one of their respective ends 7, the other of the respective ends of the links being respectively connected to said foot and said pressure plate. Raising the lever 1 causes the foot 2 to pivot in relation to the first pressure plate 3. The associated links 5, 6 raise the second pressure element 4 which bears against the tree sawcut consequently felling same. The pressure element 4 shown may be replaced by a plurality of toothed or roughened rollers (11 Figs. 4-6). <IMAGE>

Description

SPECIFICATION A Tree Felling Jack This invention relates to a manually operated jack for use in tree felling, and particularly to be used for the directed felling of rooted trees.

It is an object of this invention to provide a tree felling jack which is lightweight, stable and structurally simple which can be effectively used with a minimum of wasted tree wood.

According to this invention there is provided a manually operated jack for use in tree felling comprising an elongated manually operable lever having in the region of one end a foot, a pressure plate hinged to said foot and a pressure element or elements connected in spaced relation to said pressure plate and foot by two links pivotally interconnected with said pressure element or elements at one of their respective ends, the other of the respective ends of the links being pivotally connected respectively to said foot and said pressure plate.

The foot preferably extends along the axis of the lever, which may have a handle at its other end.

The links and the pressure element are preferably mutually pivotally interconnected by engaging a common bolt or axle and a plurality of parallel links may extend between the axle and the foot and the pressure plate.

One preferred pressure element is a second pressure plate pivotable about the common axle, being substantially rectangular in shape and protruding only very slightly if at all above the surface of the foot and pressure plate when the jack is in the horizontal, insertion ready position.

Such secondary pressure plate is preferably of smooth low friction surface, having a round chamfered leading edge.

Preferred pressure elements include a plurality of cylindrical rollers, freely rotational about their central longitudinal axis on the common axle.

Again, these rollers may only protrude slightly above the surface of the foot and pressure plate when same are level.

The rollers may be provided with teeth or other rough surface to help increase frictional grip with the three fibre.

Preferably the pressure plate hinged to the foot has projections from its outwardly presented surface for similar purpose.

The active surface area of the roller incorporated jack may be increased by using some in conjunction with a separate pressure plate which is pushed into engagement with the work by the rollers upon actuation of the jack. In order that such a plate will not fall off the rollers the plate may be provided with a trak or channel in that surface which engages the rollers in operation. Furthermore the lateral width of such channel corresponds approximately to the lateral distance occupied by the rollers and links on their common axle.

Such modification of the plate eases the insertion operation of same, avoiding the necessity to hold the same and simultaneously operate the jack.

Alternatively or additionally such extra pressure plate may be magnetized for greater adhesion to the rollers, eliminating the need to hold said plate in position.

A platform may be incorporated in the foot which serves to support or catch the underside of the pressure elements from sudden impact encountered in wind felling.

The link or links pivotally connected to the foot and pressure plate from the common axle may be identical.

With a secondary pressure plate acting as the pressure element, the jack is particularly useful in felling soft wooded or rotten trees. The surface area of such secondary plate is designed to support soft wood trees without damaging same under influence of the forces acting through the jack.

Both embodiments of the jack will operate within a smaller sawcut than the model disclosed in U.K. Specification 1,507,749 with a consequent reduction in wasted wood. This is effected by reducing the thickness of the tool to be inserted in the sawcut.

The embodiment employing rollers is especially useful in felling hardwood trees, the jacking tool taking advantage of the wedge shape cut in the three and being insertable further towards the felling hinge when the tree sways in the wind.

Springs and guiding members are eliminated from the structure which are prone to distortion or breakage. The tool structure is lightweight with few moving parts which considerably reduces manufacturing costs.

The jack according to this invention may be used effectively in a wedge cut above the main horizontal sawcut, the jack not needing manual support until the felling is effected by levering on the handle.

Two embodiments of the invention will now be described by way of example with reference to the accompanying drawings, in which: Fig. 1 is a side elevation of the plate version extended, Fig. 2 is a plan view of the plate version unextended, Fig. 3 is a side elevation of Figure 2, Fig. 4 is a side elevation of the roller version unextended, Fig. 5 is a side elevation of the roller and plate combination unextended, and Fig. 6 is a perspective view of the multi roller version extended.

Referring firstly to Figures 1 to 3, a lever 1 is connected to a foot 2 which is hinged upon an axle 13 to a pressure plate 3. A first link 5 is pivotally hinged to the foot 2 by an axle 9 and pivotally hinged to a second pressure plate 4 by an axle 7. This same axle 7 also pivotally engages a second link 6 to the second plate 4, the other end of the link 6 being pivotally hinged to the first pressure plate 3 by an axle 8. A platform 15 is provided between axle 9 and axle 13 which serves to absorb impact on rebound to the pressure plate 4, relieving these said axles of stress in a tree swaying situation.

The first pressure plate 3 has projections 10 for engaging with tree fibre when the jack is inserted into a sawcut. Insertion in a narrow cut is effected with the configuration of Figure 3.

Raising the lever 1 causes the foot 2 to pivot in relation to the first pressure plate 3 which remains gripping the tree fibre. The hinged links 5, 6 cause the second pressure plate 4 to be displaced away from the first plate 3 until it engages the tree fibre on the complementary side of the sawcut. Further levering on the handle 1 pushes the tree away from the cut and is consequently felled.

In Figures 4 to 6 the pressure plate is basically replaced by a plurality of cylindrical rollers 11 which has either teeth 12 or similar rough surface. The roller version is mainly useful on hard wood trees such as pine, although by using same with an additional pressure plate 14 (Figure 5) soft wood or rotten trees may be successfully felled, the roller version alone being particularly suited to wind felling.

Claims

1. A manually operated jack for use in tree felling comprising an elongated manually operable lever having in the region of one end a foot, a pressure plate hinged to said foot and a pressure element or elements connected in spaced relation to said pressure plate and foot by two links pivotally interconnected with said pressure element or elements at one of their respective ends, the other of the respective ends of the links being pivotally connected respectively to said foot and said pressure plate.

2. A jack in accordance with Claim 1, wherein the links are pivotally interconnected by engaging a common axle and wherein a plurality of parallel links extend between the axle and both of said foot and said pressure plate.

3. A jack in accordance with either preceding claim, wherein the pressure elements are cylindrical rollers rotational about a common axle.

4. A jack in accordance with Claim 3, wherein the rollers are provided with teeth or other rough surface.

5. A jack in accordance with Claim 1 or 2, wherein the pressure element is a secondary pressure plate having a smooth, low friction surface and a round chamfered leading edge.

6. A jack in accordance with any preceding claim, wherein the pressure plate has projections which engage frictionally with wood fibre.

7. A jack in accordance with Claim 1, 2 or 6, wherein the pressure elements are a plurality of rollers engaged on a common axle in combination with a separate pressure plate.

8. A jack in accordance with Claim 7, wherein the separate pressure plate has a channel in that surface which engages the rollers, the lateral width of said channel being approximately equal to the lateral distance occupied by the rollers and links on their common axle.

9. A jack in accordance with Claim 7 or 8, wherein the separate pressure plate is magnetized.

10. A jack in accordance with any preceding claim, wherein one or more shock absorbing plafforms are positioned in the foot.

11. A jack in accordance with any preceding claim, wherein the links pivotally connected to the foot and pressure plate are identical.

12. A jack in accordance with any preceding claim, wherein the foot extends along the axis of the lever, which latter has a handle at its other end.

13. A manually operated jack for use in tree felling constructed and arranged to function substantially as herein described and as shown in any of the Figures in the accompanying drawings.