The present invention relates to a collapsible spa¬ de comprising a handle; a shank that is rotatably connec- ted to the handle by a first joint; and a blade that is rotatably connected to the shank by a second joint, whe¬ reby the shank consists of a pull rod that is connected to the- handle and the blade by said joints, and a locking device for the spade which consists of a shank tube that encloses the pull rod and a sleeve located at one end of the shank tube, whereby the shank tube and the sleeve have cooperating means, which cause the length of the locking device to alter, when the sleeve is turned around its cen¬ tre axis, to lock the spade in the extended position and to release the joints so that the spade can be folded, and whereby both ends of the locking device have a contact surface, one located in the shank tube and the other in the sleeve, and the handle and the blade have contact sur¬ faces, which in cooperation with the contact surfaces of the locking device lock the spade in the extended positi¬ on.

Collapsible spades are used in place of conven¬ tional spades when transporting a conventional spade to the excavation site causes difficulties due to the length and/or weight of the spade. Collapsible spades are usually used by wanderers and in the army.

Known collapsible spades of the kind described abo¬ ve assume the shape of a flat Z in the collapsed state, whereby the handle is located on one side of the shank and the blade on the other. The spade can be put into working position by folding out the handle and the blade so that they form an essentially straight extension of the shank, whereafter the locking device is extended by turning the sleeve of the locking device so that the ends of the locking device abut on the handle and the blade, which are

interconnected by an inextensible pull rod so that the three parts of the spade form a rigid unit.

In one known construction, the pull rod has a rec¬ tangular cross-sectional shape and the sleeve is located at that end of the locking device which is closest to the blade. The locking device has two attaching lugs for the pull rod, the edges of which form the contact surface of the blade. Since the sleeve should be able to rotate around the pull rod, it has a circular opening with a dia- meter corresponding to the maximum extension of the pull rod in the lateral direction.

This known spade has certain drawbacks. The grea¬ test drawback is that the second joint between the shank and the blade, which is most heavily loaded, is also the weakest joint in this known construction. The contact sur¬ face of the blade cannot for practical reasons be dimen¬ sioned so as to be large; it is only composed of the edges of the attaching lugs. Due to the relatively large central opening, the contact surface of the sleeve is composed of a relatively narrow ring between the edge of the central opening and the periphery of the sleeve, wherefore the contact surface of the sleeve is also very limited. Owing to this construction, the sleeve is either deformed at those points where the attaching lugs of the blade abut on the sleeve, as a result of which the blade is no longer in line with the shank, or the sleeve has to be made of a very strong material, which increases the manufacturing costs. The great force with which the attaching lugs of the blade abut on the sleeve may also deform the threads of the sleeve and the shank tube, and this may make it difficult to turn the sleeve to adjust the length of the locking device. A further drawback of this known construc¬ tion is that impurities, such as sand and gravel, may en¬ ter the sleeve through its central opening, which is con-

siderably larger than the cross section of the pull rod, as mentioned above, causing functional disorders.

The object of the present invention is to achieve a collapsible spade in which the sleeve is subjected to con- siderably less stress and is less sensitive than in known constructions to external impurities. The collapsible spa¬ de according to the invention is characterized in that the contact surface of the sleeve is arranged to cooperate with the contact surface of the handle and the contact surface of the shank tube is arranged to cooperate with the contact surface of the blade.

Placing the sleeve at that end of the shank, which is close to the handle, presents several advantages. The contact surface of the handle can for natural reasons be dimensioned so as to be large, whereby the limited contact surface of the sleeve can be utilized in its entirety. The danger of impurities entering the sleeve is also reduced, since the opening of the sleeve is located at a distance from the blade of the spade. By subjecting the first joint between the handle and .the shank to a smaller momentum than the second joint, the danger of deformation of the sleeve and/or the threads of the sleeve and of the shank tube is also reduced.

The fact that the contact surface of the shank tube cooperates with the contact surface of the blade also pre¬ sents considerable advantages. Since the shank tube cannot be brought to rotate around the pull rod, the opening at the end of the shank tube can be adjusted as regards its shape to the cross-sectional shape of the pull rod, whe- reby the opening can be dimensioned so as to be relatively small so that the pull rod is only surrounded by a narrow slit. Consequently, impurities cannot easily enter the shank tube and the shank tube is provided with a large contact surface against the contact surface of the blade, thus enabling a more even distribution of the great forces

that arise in the joints, when the spade is used. The more even distribution of the forces permits the use of plastic to a greater extent even as the material for the shank tu¬ be. An especially advantageous embodiment of the spade according to the invention is characterized in that the contact surface of the shank tube has a central opening for the pull rod and side openings, and that the contact surface of the blade has protruding sections which are ar- ranged to shoot into the side openings when the spade is locked in this extended position.

By providing the contact surface of the shank tube with openings in which protruding sections of the contact surface of the blade are meant to shoot into, the advan- tage is achieved that the stresses which in known const¬ ructions are concentrated to two narrow zones on the con¬ tact surface of the shank tube are partly transmitted to the pull rod via the protruding sections of the blade, which exerts a load that is perpendicular to the longitu- dinal axis of the shank tube. Since part of the load on the second joint is thus transmitted to the pull rod, the shank tube is subjected to a lesser load than in known constructions, and it can thus be made of a weaker mate¬ rial, e.g. plastic. The manufacture of the shank tube is simplified, if the side openings are protuberances of the central open¬ ing.

The protruding sections on the contact surface of the blade are preferably composed of teeth located on the edge of the attaching lugs. The blade can thus be easily locked into different angle positions relative to the shank if each attaching lug has at least two teeth.

The shank tube can very well be made of plastic if the contact surface of the shank tube is located on a pla- te that is arranged so as to be perpendicular to the Ion-

gitudinal axis of the shank, that surrounds the pull rod and that is composed of a harder material than the shank tube. The plate is preferably made of metal, e.g. steel.

An advantageous embodiment of the spade according to the invention is described in greater detail in the following with reference to the enclosed drawing, in which

Figure 1 shows a plan view of the spade,

Figure 2 shows a side view of the spade,

Figure 3 shows the spade in the collapsed position, Figure 4 shows the centre part of the spade, partly in a longitudinal section, in the locked position of the spade,

Figure 5 shows, as Figure 4, the spade in its un¬ locked position, and Figure 6 shows a section along the line VI-VI in

Figure 4.

The collapsible spade shown in the drawing compri¬ ses a handle 1, a shank 2 and a blade 3. The handle is rotatably connected to the shank by a first joint 4 and the shank is rotatably connected to the blade by a second joint 5.

The handle 1 is preferably made of plastic and it has the trapezoidal shape of the embodiment shown in the figure. The spade blade is preferably made of metal and it has two parallel attaching lugs 6 for the joint 5. The shank 2 is primarily composed of a pull rod 7 connected at its end to the handle and the blade by the joints 4, 5, and a locking device 8 for the spade which surrounds the pull rod in the area between the handle and the blade. The pull rod 7 has an essentially rectangular cross-sectional shape and it is preferably made of metal, such as alu¬ minium, whereas the locking device 8 has of an essentially circular cross-sectional shape and is made mainly of plas¬ tic.

The locking device 8 is composed of a shank tube 9 surrounding the pull rod 7, and a sleeve 10 located at one end of the pull rod on its outside. The outer surface of the shank tube and the inner surface of the sleeve have threads 11 which engage. That end of the sleeve 10 which is closest to the joint 4 is provided with a plastic plate 12 inside the sleeve and the pull rod 7 is provided with a through peg 13. Two helical springs are arranged between the plate 12 and the peg 13, and these springs strive to enlarge the distance between the plate 12 and the peg 13. That end of the shank tube 9 which is closest to the joint 4 has a plate 15 that is perpendicular to the longitudinal direction of the pull rod 7 and that has a central opening 16 for the pull rod. The locking device 8 has a contact surface at both ends. One contact surface is composed of the annular end surface 17 of the sleeve and the other of the free surface on the plate 15 of the shank tube. The contact surface of the handle has been indicated with the reference number 18 and the contact surface of the blade, which contact sur¬ face is composed of the edges of the attaching lugs, with 19.

In accordance with the invention, the sleeve 10 of the locking device 8 is placed at that end of the locking device which is closest to the handle 1, whereby the con¬ tact surface 17 of the sleeve cooperates, as a result, with the contact surface 18 of the handle, whereas the contact surface on the plate 15 cooperates with the con¬ tact surface 19 of the blade. It can be seen from Figures 4 and 5 that the at¬ taching lugs 6 of the blade have two teeth 20 and 21, which protrude from the edge of the attaching lugs. From Figure 6, it can be seen that the plate 15 has, in addi¬ tion to the central opening 16, side openings 22 which are located on both sides of the central opening at a plane

that is essentially parallel to the blade 3. In the embo¬ diment according to Figure 6, the side openings 22 are protuberances of the central opening 16.

The side openings 22 are dimensioned so that they admit the teeth 20 or 21 to lock the blade 3 in the desired position relative to the shank 2 and to transmit part of the load exerted by the blade on the shank tube to the pull rod 7 via the plate 15.

The spade is locked into the working position and collapsed in the following manner. When the handle, the shank and the blade are in the position that is shown in Figure 1, the sleeve 10 is turned in such a direction that the total length of the locking device 8 increases. Since the distance between the joints 4 and 5 cannot increase due to the pull rod 7, the contact surfaces 17, 18, the surface 15 of the plate 15 and the surface 19 are finally brought into contact with one another, whereby the spade is locked in the extended use position, see Figure 4. To collapse the spade, the sleeve 10 is turned in the op- posite direction, whereby the total length of the locking device 8 is reduced and the contact between the surface of the plate 15 and the surface 19 ceases due to the action of the springs 14, see Figure 5. This makes it possible to turn the blade 3 on the shank 2 and the handle 1 under the shank, concerning the position of the spade in Figure 2, see Figure 3. The blade and the shank can also be locked into a position in which they together form an angle of approximately 90°, cf. the dashed lines in Figure 2. In this case, the teeth 21 are located in the side openings 22 of the plate 22.

The invention is not restricted to the embodiment described above but it can vary within the scope of the enclosed claims. It is thus possible to make the parts of some other material than that mentioned above and thus the plate 15 can be replaced by a thick wall made of plastic.

The side openings 22 and the teeth 20, 21 can be left out or the side openings 22 can be separate openings that are not in contact with the central opening 16. The attaching lugs 6 of the blade are, in the illustrated embodiment, arranged on opposite sides of the pull rod 7, but they can be replaced by some other suitable construction. The num¬ ber of teeth 20, 21 on the edge of the attaching lugs may also differ from that stated above.