LOWERING MECHANISM FOR HAND-OPENED LIFTING TOOL

Description

Field of Invention

[0001] The invention relates to a hand held jacking mechanism, more specifically to a lowering mechanism for a hand held tool for jacking and levelling of objects using a caulking gun jacking mechanism.Background

[0002] A caulking gun is well known in the tool industry and has been on the market for several decades. They include a pumping or jacking mechanism for example described in US 4009804. This mechanism is cheap and easy to produce and has minimal friction under operation.

[0003] The inventor has invented a hand held tool for jacking and levelling of objects using a caulking gun jacking mechanism. The caulking gun jacking mechanism is a one way jacking system. It is possible to jack a frame with such a jacking mechanism upwards along a jacking shaft. When the frame is released it is 'falling' uncontrollably along the jacking shaft. This invention will control the downward movement of the frame along the jacking shaft in a caulking gun jacking mechanism in an adjustable stepwise manner.

[0004] DE10127718A1 discloses a jack that has a rod and a pair of tongs with interconnected tong halves of which one half has a first handle and operating part and the second half has a second handle and operating part. A lifting disc is mounted displaceable on the rod which in turn passes through the two operating parts. Compression springs are provided whereby the first both lifts the lifting disc along the rod and presses the first and second handle parts apart whilst the second spring is used to pretension the lowering plate in the lift direction and lift it along the rod. The first lowering plate is connected in an inclined position to the rod for swivel movement with the first operating part.

[0005] GB2416528 discloses a manually operated jacking device, the device comprising: a support; at least one elongate member extending from the support in a longitudinal direction; an elongate driving member arranged in use to move in the longitudinal direction relative to the elongate member; a contact member constrained to move with the driving member and arranged in use to engage an object to be jacked; wherein a jacking mechanism distal from the support is arranged, in a jacking condition, to move the driving member and the contact member in a jacking direction with the contact member moving relative to the support and, in a release condition, the driving member and contact member are able to move relative to the support.

[0006] US5622355 discloses a lifting and supporting apparatus having a vertically oriented robe interconnected to a smaller, vertically oriented rod by a lifting device. A large bracket or the like is secured to the robe so as to provide a surface upon which an object can rest. The lifting device provides a means by which to move the rod downwardly with respect to the tube, thus allowing both the tube and the object to be easily raised and supported above the ground upon which the rod rests.

[0007] JP4206503B1 aims to provide a compact, user-friendly and economical hand jack capable of raising a steel sash frame located in a chipped hole without causing damages on the steel sash frame, capable of being operated to freely adjust vertical height to a target position and also capable of being operated to make easy positional adjustment in the back and forth / right and left directions. According to the suggested solution, the height in the lowering direction can be continuously adjusted by turning an adjustment handle provided at the rear end of a rod of the hand jack. A support section is provided at the tip end of an arm. The support section can be lowered to a position lower than a base fixed to the tip end of the rod, and a protective member for preventing an object to be raised from being damaged is provided on the base end section of the arm. The object to be raised is supported at two points, i.e., the protective member and the support section. Therefore, the object can be stably held on the support section to maintain a posture in parallel with the object.

[0008] US2820608 discloses a lifting device or jack by means of which a load may be raised or lowered in a step-wise manner. The jack includes a substantially vertical elongated shaft. A bifurcated support member is mounted on the shaft for upward and downward sliding movement relative thereto. The support member has a pair of spaced substantially horizontal upper and lower prongs and which are respectively formed with apertures and therethrough. A support element is connected to the support member. The support element may be inserted into a receiving sleeve or the like which forms part of the load to be raised and lowered by the jack. The jack further includes first, second and third clamping members arranged between the prongs.

[0009] US5385335 disclose an apparatus for lifting modular furniture. The apparatus comprises a central shaft and housing slidably mounted on the shaft. Either the housing or the shaft is supported by a base support and the other of the housing and shaft is moveable. The apparatus further comprises a jig which is adapted to mate with the furniture to be lifted, and means for raising and lowering the jig to thereby raise and lower the furniture. The apparatus further includes a lateral stabilizer which stabilizes the furniture once it is raised off the floor.

[0010] GB525211 discloses a vehicle jack. The jack is primarily designed to engage the bumper or another projection on an automotive vehicle in order to elevate the body, springs, chassis, and wheels. Due to the resilient connection between the body and wheels, it is necessary that the jack move throughout a relatively large range of movement. The jack construction is of the friction type in which locking plates are used for the purpose of not only effecting an elevation of the particular object being lifted but also for preventing downward movement. By connecting a removable lifting handle directly to the locking plates, downward movement may be activated.Summary of invention

[0011] The invention describes a hand held jacking tool comprising a jacking frame a jacking shaft and a caulking gun jacking mechanism comprising at least one jacking plate biased towards an open state and at least one holding plate, above the jacking plate, being biased towards a gripping state. The hand held jacking tool further comprises a lowering mechanism which comprises a lowering plate on top of the holding plate being parallel to the holding plate when not activated. The lowering mechanism further comprises a pushing lever, a hinge attachment connecting the pushing lever to the lowering plate at a rear end towards an operating handle and a pivot structure connected to the pushing lever or holding plate a distance backward from the hinge attachment. The lowering mechanism further comprise a spring biasing the lowering plate towards the holding plate. The lowering plate is lifted up and grips the jacking shaft when the pushing lever is pushed downwards and pivots around the pivot structure and in turn pushes the holding plate downwards loosening it from the jacking shaft and moving the frame down along the jacking shaft a distance until the holding plate reaches an angle that stops it against the jacking shaft while the lowering plate still grips the jacking shaft.Brief description of the drawings

[0012] To improve the understanding of the application the following drawings have been supplied. Like numerals in different drawings represent the same features. Fig. 1 shows the entire hand held tool. Fig. 2 shows the frame of the tool with the lowering mechanism. Fig. 3 and 4 shows perspective views of an embodiment of the lowering mechanism on top of the holding plates. Fig. 5 shows a sectional side view of an embodiment of the lowering mechanism with an M-shaped spring. Fig. 6 shows a sectional side view of an embodiment of the lowering mechanism with 15 a spring shaped like a half M. Fig. 7a, b and c shows activation of the lowering mechanism. Fig. 8 shows a lowering plate with a M-shaped spring. Fig. 9a and b shows three holding plates in perspective view and from the side respectively. Detailed description of preferred embodiments

[0013] We will describe the invention with directions up - down as seen in figure I and rear as pointing towards the user. The rear is the side of the operating handle 7, as seen in figure 1, and the front is the opposite side, or, in other words, the direction in which the feet are pointing.

[0014] The invention describes a lowering mechanism 12 for a hand held jacking tool 20 comprising a jacking frame 11 a jacking shaft 3 and a caulking gun jacking mechanism. The jacking mechanism normally comprises a jacking plate I biased towards an open state and a holding plate 2 above the jacking plate I being biased towards a locked state as can be seen in figure 1 and 2. The plates are moveable along a jacking shaft 3 and are able to grip the jacking shaft 3. It may be an advantage to have more than one plate, for example two or three parallel plates as seen in figures 9 a and b. This will reduce the wear on jacking shaft and plates and prolong the life of the mechanism, it will also provide a better grip as contact will be made on several contact regions. To obtain this effect the holes must have same size.

[0015] The plates 1, 2, moving along the jacking shaft in a caulking gun jacking mechanism, comprises holes slightly bigger than the cross section of the jacking shaft. When the plates are at a right angle with the jacking shaft the plates are moving freely along the shaft. When the plates have a different angle with the jacking shaft the plates will grip and lock to the jacking shaft. This is the main principle in a caulking gun jacking mechanism. In this text we call the two states the open state (right angle) and the gripping state (not a right angle). When we describe the different plates 1, 2, 4 in this text we will automatically assume that a suitable hole, as shown in fig. 9a, to fit the jacking shaft is provided.

[0016] The lowering mechanism according to the invention comprises a lowering plate 4 on top of the holding plate 2 being in the same gripping state as the holding plate when not activated. This corresponds to the lowering plate being parallel with the holding plate. The lowering mechanism will then be in the position as seen in figure 7a.

[0017] The lowering plate is activated by a pushing lever 5 connected with a hinge attachment 6 to the lowering plate at a rear end towards an operating handle 7, wherein the pushing lever is pivoting around a pivot structure 8 connected to the lever or holding plate a distance backward from the hinge attachment, causing the lowering plate 4 to grip the jacking shaft 3 when the lever is pushed downwards. When the lowering plate grips the jacking shaft a further push on the lever 5, by the operator, will push the holding plate downwards and loosen it from the jacking shaft as seen in figure 7b. This will allow the frame to move downward along the jacking shaft a distance until the holding plate reaches an angle that stops it against the jacking shaft 3 while the lowering plate still grips the shaft. This leaves the lowering plate and the holding plate with a distance between them. If the holes for the jacking shaft in the lowering plate and the holding plate have the same size the two plates will also be mainly parallel as seen in fig. 7c. The frame has moved down along the jacking shaft a distance determined by the pivoting action of the lever while the lowering plate 4 is stopping the frame from further downward movement. The distance the frame is moving is fairly similar to the distance between the parallel lowering plate and holding plate seen in fig 7c. This correspond to the vertical component of the angular movement of the arm between the hinge attachment 6 and the pivot structure 8 from the position where the pushing lever 5 causes the lowering plate to grip the jacking shaft. When the pushing lever 5 is released the spring 9 forces the lowering plate down towards the holding plate and the lowering mechanism is back to the position seen in fig. 7a.

[0018] The pivoting action of the lever 5 is determined by a first pivot point, P1, at the front end of the lowering plate, as seen in fig 5, the hinge attachment 6, H1, and a second pivot point, P2, associated with the pivot structure 8 and finally the force applied to the lever and the length of the lever arm. This is shown in figure 5. The positional distribution of P1, P2, H1 and F1 are hard to calculate and have to be tested and tried. If the distance H1-P2 is to big related to the distance P1-H1 and P2-F1 the mechanism will simply release the frame as with the old version. If the distance H1-P2 is too small related to the distance P1-H1 and P2-F1 the mechanism 12 will not be activated. However, the length of arms and position of pivot points must be such that an activation force used on the pushing lever 5 to cause the lowering plate 4 to grip the jacking shaft 3 must be less than the force needed to release the holding plate 2. The activation force must also counter the force of the spring 9 holding the lowering plate down. Therefor the length of the pushing lever rearward of the pivoting point 8 must be longer than the distance between the pivot point 8 and the hinge attachment 6, preferably more than twice the distance.

[0019] The lowering plate is held in place by a spring 9 biasing at least the front side of the lowering plate towards the holding plate. Two embodiments of the spring are shown in figure 5 and 6. One is a M-shaped spring plate and the other is a spring plate, which is shaped as a half M. Advantageously the spring is held in place by a holding structure 13, as shown in fig. 8, through which the holding plate (s) will fit as shown in figure 3 and 4 and in particular fig. 8, thus holding the spring to the holding plate(s). In one embodiment the spring is an M-shaped spring plate 9 with a hole for the jacking shaft and holes for the holding plate(s) in the respective legs of the M-shape on each side of the jacking shaft.

[0020] The lowering mechanism is not very sensitive to the strength and positioning of the spring 9, whose main purpose is to push the lowering plate back down towards the holding plate. However, we found that it was best to avoid positioning a center of force too close to the hinge attachment 6. Preferably the center of force is positioned in front of the center of the lowering plate as seen in the figures.

[0021] The lowering mechanism is sensitive to the gap between the front and rear sides of the jacking shaft and the holes in the holding and lowering plates 2, 4. This distance should be less than a millimeter. Preferably between 0,02 and 0,3 mm. Larger shafts allow for larger gap. If the gap is too big the grip of the holding plate will weaken and if it is too small, it will tend to jam.

[0022] In one embodiment the rear end of the pushing lever and a release lever 10, which is an extension of the holding plate 2, is positioned beside each other for easy operation by the thumb of an operator as seen in figure 3, 4.Inventory

[0023] 1 Jacking plate 2 Holding plate 3 Jacking shaft 4 Lowering plate 5 Pushing lever 6 Hinge attachment 7 Operating handle 8 Pivot structure 9 Spring 10 Release-lever 11 Jacking frame 12 Lowering mechanism 13 Holding structure 20 Hand held jacking tool

Claims

1. A hand held jacking tool comprising a jacking frame (11), a jacking shaft (3) and a caulking gun jacking mechanism comprising at least one jacking plate (1) biased towards an open state and at least one holding plate (2), above the jacking plate (1), being biased towards a gripping state, the hand held jacking tool comprising a lowering mechanism, wherein the lowering mechanism is comprising: a lowering plate (4) on top of the holding plate(s) (2) being parallel to the holding plate(s) (2) when not activated, a pushing lever (5), a spring (9) biasing the lowering plate (4) towards the holding plate, wherein the lowering mechanism is characterized by further comprising: a hinge attachment (6) connecting the pushing lever (5) to the lowering plate (4) at a rear end towards an operating handle (7), a pivot structure (8) connected to the pushing lever (5) or holding plate(s) (2) a distance backward from the hinge attachment (6), wherein the lowering plate (4) is lifted up and grips the jacking shaft (3) when the pushing lever (5) is pushed downwards and pivots around the pivot structure (8) and in turn, pushes the holding plate(s) (2) downwards loosening it from the jacking shaft (3) and moving the frame down along the jacking shaft a distance until the holding plate(s) (2) reaches an angle that stops it against the jacking shaft while the lowering plate still grips the jacking shaft.

2. The hand held jacking tool according to claim 1, wherein the rear end of the pushing lever (5) and a release lever (10), which is an extension of the holding plate is positioned beside each other for easy operation by the thumb of an operator.

3. The hand held jacking tool according to claim 1, wherein the spring (9) is an M-shaped spring plate with a hole for the jacking shaft and a holding structure (13) in the respective legs of the M-shape on each side of the jacking shaft for holding the spring to the holding plate(s).

4. The hand held jacking tool according to claim 1, wherein the spring (9) is a spring plate shaped as a half M with a holding structure (13) in the leg of the half M for holding the spring to the holding plate(s).

5. The hand held jacking tool according to claim 3 or 4, wherein the holding structure (13) is a hole through which the holding plate(s) (2) will fit.