The present invention relates to a tool for opening connection joints for chains. Such connection joints consist of two callipers linked by a cross pin. The cross pin includes a spring holding it in place in the connection joint. Most often, the joint is put together using a hammer, i.e. the cross pin is hammered until it is in mesh. Correspondingly, the joint is opened by forcing the cross pin out with a hammer and mandrill. This process may be difficult, as "in the field" there may be no possibility of mounting the joint firmly; injuries may occur if the mandrill slips, etc.

Thus, there is a need for a tool for opening connection joints in a controlled way.

This is achieved with a tool according to the invention, as it appears from the following claims.

The invention will now be described in relation to the appended Fig. 1, which shows the tool as seen from the side. The tool includes a longitudinal frame or chassis 1. To the chassis 1 there is fastened a locking arm 2 which may be rotated around the bolt 3. In use, the connection joint is placed in the chassis whereupon the locking arm is rotated into position holding the joint in place. At the end of the locking arm there is a groove 4 adapted to engage a corresponding bolt 5 at a first end of the chassis. A locking screw may be arranged to secure the locking arm to the bolt 5 when the arm is closed upon the joint. Below the bolt 5 there is mounted a counterhold (sleeve) 13 (shown dashed in the figure). The counterhold may be interchangeable to adapt to cross pins of various sizes. The chassis 1 also includes a press cylinder 6 (dashed) which is mounted in the other end of the chassis. The press cylinder includes a piston 8. At the end of the piston there is fastened a mandrill 9. The mandrill is interchangeable with mandrills of different sizes suiting the size of the cross pin in the coupling joint. The press cylinder is manoeuvred with a lever 10, as in a car jack (this means that the lever is connected with a small jack cylinder delivering oil to the press cylinder). By pumping the lever, the mandrill 9 may push the cross pin out of the coupling joint and out through the counterhold 13. When the pin has been pushed out, the piston and mandrill may be returned to the original position by opening a valve in the press cylinder using the handle 11. A spring (not shown) located below the press cylinder will then pull the piston and mandrill back. The locking arm may then be opened releasing the coupling joint. The tool may also be used for the opposite operation, to mount the cross pin when reassembling the joint.