Background of the Invention A rescue tool of this kind is nowadays a frequently used implement at rescue operations, where a vehicle has to be cut-up or opened, for example for freeing a person trapped in the vehicle. Extremely high forces act within the tool at use, which makes it important to provide a satisfactory guiding for the piston in the cylinder.

At the same time the weight and dimensions of the tool have to be kept down, among other things because the tool is hand-held. For this reason it may be difficult to obtain a sufficient guiding length for the piston in the cylinder. It is accordingly a main object of the invention to obtain the longest possible guiding length for the piston without adding to the overall length of the tool.

The Invention This is according to the invention obtained in that the yoke is provided with an external, generally cylindrical yoke guide with an outer diameter corresponding to the inner diameter of the cylinder.

Hereby the guiding length will be as great as possible and independent of the position of the piston. No length is added to the tool. Due to the fact that the distance between the two guides is so great, the axial length of each guide (i. e. the length of the piston and of the yoke guide) can be kept at a minimum.

Brief Description of the Drawings The invention will be described in further detail below under reference to the accompanying drawings, in which the different Figures are drawn to different scales and in which Fig 1 is a side view of a rescue tool embodying the invention, Fig 2 is a partly sectional view of a part of the rescue tool according to Fig 1 along the line II-II in Fig 1, Fig 3 is a view corresponding to Fig 1 of the forward part of the rescue tool with a portion sectioned, Figs 4-6 are a side view, a partly sectional top view, and an end view, respectively, of a yoke in the rescue tool embodying the invention, and Figs 7-9 are a side view, a section along the line VIII-VIII in Fig 7, and a top view, respectively, of a yoke guide in the rescue tool embodying the the invention.

Detailed Description of a Preferred Embodiment A rescue tool 1 of the kind shown in an overall view in Fig 1 is well known in the art. The tool is provided with hoses 2 and 3 for the supply to and removal from the tool of high pressure hydraulic fluid from and to, respectively, an external source therefore. The tool is provided with internal means to be described for transforming the hydraulic pressure into a spreading or cutting movement of arms 4 and 5 pivotably attached to the body 6 of the tool at 7. The tool is provided with a handle 8 for its positioning and manipulating.

As the rescue tool 1 is well known in the art, the description of its known parts will be kept brief.

Referring to Fig 2, a double-acting piston 9 is axially movable in a cylinder 10. High pressure hydraulic fluid can alternatively be supplied directly to the left of the piston 9 for movement of the piston to the right or

- through a tube 11 and a bore 12 - to the right of the piston 9 for movement of the piston to the left. A sealing arrangement 13 is provided to the right of the piston 9 in the cylinder 10.

From the piston 9 a hollow piston rod 14 extends to the right in Fig 2 through the sealing arrangement 13. A yoke 15 to be further described below is threadingly attached to the piston rod 14. Two force-transmitting links 16 and 17, which are most clearly shown in Fig 3, are at their inner ends pivotably attached to the yoke 15 and at their outer ends to the cutting and spreading arms 4 and 5, which are pivotably mounted on a common pivot shaft 7 in the cylinder 10. By this arrangement the arms 4 and 5 will open or spread at a movement of the piston 9 to the left in Fig 2 and move together (for a cutting action) at a movement to the right of the piston 9.

A generally cylindrical yoke guide 18 to be further described below is attached to the yoke 15 by means of two screws 19 and is guided by the cylinder 10 for axial movements therein.

The yoke 15 is shown in Figs 4-6. From right to left in Figs 4 and 5 (left to right in Figs 2 and 3) the yoke 15 has the following portions : a cylindrical stem 20 (with a circumferential groove 21 for a sealing ring 22, Figs 2 and 3) for closing insertion in the hollow piston rod 14, a threaded portion 23 for attachment to the piston rod 14, and a fork-shaped yoke portion 24 having two through bores 25 for the pivotal attachment of the two links 16 and 17 as well as a threaded hole 26 for the screws 19, intended for the attachment of the yoke guide 18.

The yoke guide 18 is shown in Figs 7-9. It is basically a hollow cylinder with an outer diameter corresponding to the inner diameter of the cylinder 10 and an inner diameter corresponding to the outer diameter of the yoke portion 24. The yoke guide 18 has two axial slots

18'for the yoke portion 24 to laterally extend out through. Also the cylinder 10 has axial slots in this region for the yoke portion 24. For the attachment to the yoke 15 by means of the screws 19 the yoke guide is provided with holes 27.