The present invention relates to a lock bolt joint, e.g. in a farm implement, where an element is secured by means of a lock bolt, which is inserted in a support portion and is connected with safety means for counter¬ acting a free release of the bolt. Especially in rela¬ tion to farm implements, but also in a number of other relations it is of importance to fix machinery compo¬ nents by means of lock bolts to achieve a securing, however, possibly also to achieve a free inter-rotata- bility of the parts, and it is well-known that such a connection may be secured by applying special means that can counteract a retraction of the lock bolt in an easy and unintended manner. A traditional security in this respect is the use of a transverse cotter pin through the free end of the lock bolt, however with further application of means for securing a locking of the transverse cotter pin, e.g. a locking spring hoop.

The purpose of the invention is to provide a lock bolt joint, by which the lock bolt may be sufficiently secured in a particularly simple manner, and according to the invention this is obtained by the said safety means being constituted by permanent magnetic sub por¬ tions of or in the parts forming the joint, though pre¬ ferably with the support portion itself being non-mag¬ netized. Preferably the lock bolt itself may be magnet¬ ized such that a bolt head on the lock bolt can be mag¬ netically attracted against an outwardly exposed surface portion of the support portion, and such a magnetic engagement can be fully sufficient for securing an ef¬ fective fastening of the lock bolt.

The lock bolt itself, however, will not need being magnetized, when according to claim 3 a magnetic body is mounted between the bolt head and its cooperating en¬ gagement area of the support portion.

The lock bolt may be arrested in its inserted posi¬ tion already by the said magnetic effect, such that it

should not be additionally secured, i.e. it is securable by the very insertion, without further safety means. Therefore the bolt is particularly easy to mount, as it should just be inserted and not secured otherwise.

In the following the invention is explained in more detail with, reference to the drawing in which:-

Fig. 1 is a lateral view of the rotor of a rotary cultivator.

Fig. 2 is a partial view of the rotor, partly in section.

Fig. 3 is the same seen in the axial direction of the rotor, and

Figs. 4-8 are sectional views illustrating alterna¬ tive designs of the construction as shown in Fig. 2.

The cultivator rotor shown in Fig. 1 has a horizon¬ tal rotor shaft 4, on which is secured a number of knife holders 5 for cultivator knives 6 for working a soil area 7. On an upper cover frame 8 is mounted a rearward- ly projecting cover shield 9.

Such a machine is a good example of a construction, in which lock bolts may be advantageously used, viz. for the holding of cultivator tines that should be shiftable in an easy manner, yet be held safely against consider¬ able affections. As shown in Figs. 2 and 3 the tines 6 are held in insertion openings in the tine holders 5, these having a throughbore 12 for receiving a lock bolt 13 with bolt head 14, the bolts being inserted through respective holes in the inserted tines 6.

The lock bolt 13 is designed in accordance with the invention in such a manner that it can be held without its free end having to project out of the throughbore in the tine holder 5, and already this feature presents several advantages. In the inner side or underside of the bolt head 14 is provided an annular groove, in which is mounted an annular body 15 consisting of a permanent magnet, which forms the surface of engagement against

the side of the tine holder 5. Preferably the bolt head is countersunk in a recess in this side, such that it is protected against retraction influence from outside; also the free end of the bolt is located in a protected manner inside the throughbore in the holder 5, so that neither here the bolt can be subjected to unintensional release actions, and at least in a very large number of applications the bolt will hereby be held in a suffi¬ ciently safe manner solely by the action of the magnetic body 15. On the other hand, however, the bolt will be very easy to dismount when intended, viz. just by a simple pressing out from the free end thereof.

For the magnetic holding of the bolt it is suffient that the annular magnet 15 is placed between the bolt head 14 and the side of the holder 5, i.e. the magnet should not necessarily be mechanically held by the bolt head. However, such a permanent holding is advantageous in that the bolt will then be a special "magnet bolt" that can be kept on store and be used and reused in different connections. Inversely, however, as shown in Fig. 4, it may be the receiving support portion 5 which is provided with the magnetic ring 15 embedded in a recess 16, whereby this construction part may receive ordinary lock bolts or rather simplified lock bolts 17 consisting solely of a shank and a head, the bolt of course being of iron.

It is a further possibility that such a bolt 17 is magnetized as a whole, whereby there is no need to use a separate magnetic body 15. It should be considered, however, that the available highly efficient magnet materials, which will be well suited for the separate rings 15, may not be particularly well suited as bolt materials. On the other hand there may be instances where the holding requirements are no higher than a magnetized steel bolt will be sufficient. Correspond¬ ingly it is at least a theoretical possibility that it

can be the holder portion which is magnetized.

The invention is not limited to the magnetic hold¬ ing action occurring directly between the bolt and the support portion, since as shown in Figs. 5-8 a magnetic holding may be obtained with the use of magnetic bodies that are not positioned between the bolt head and the holder portion. Thus, in Fig. 5 a magnetic disc 18 is mounted in a recess in the opposed outer side of the holder 5, such that this disc may attract and hold the free end of the bolt shank; hereby the latter does not really need having a bolt head. The said throughbore is designated 18 in Figs. 4 and 5.

In the embodiment of Fig. 6 the inserted lock bolt is covered by a corresponding magnetic disc 19, which after the bolt insertion is placed in a recess in the side of the holder portion, whereby it is held against this side and thus blocks for any stepping out of the lock bolt.

In Fig. 7 it is shown that the same arrangement will be usable in connection with a headless bolt, i.e. a pin 20, when the same is otherwise secured against stepping out through the opposite end of the throughbore 18, namely here by virtue of this bore at its right hand outer end being closed or having a reduced diameter as shown at 21. The bore, however, may be fully through- going if its end is closed in some other manner, e.g. with the use of an extra magnetic disc 19 as shown in Fig. 8.

The described lock bolt joint refers to an iron construction, but of course other materials may be pre¬ sent in the entire structure. What is essential is of course that in the holding area of the lock bolt such iron or magnet parts will be present which can fulfill the aim of the invention with respect to a magnetic locking or arresting of the lock bolt. Should the hold¬ ing portion 6 consist of wood, for example, the embodi-

ent according to Fig. 4 will provide for the desired securing, when only the magnet 15 is suitably rigidly anchored in the wood, just as the embodiments according to the other figures could be used when in the relevant end of the throughbore there is provided a fixed iron bushing.

A possible alternative for such a bushing would be a number of iron or magnet pegs inserted in bores ar¬ ranged parallel with and encircling the main throughbore 18. Hereby the discs shown in Figs. 5-8 may consist of unmagnetized iron, but it will be a further possibility to make use of 'double magnets', i.e. complementarily polarized magnets on the rigid and the loose element, respectively, whereby an extra safe holding will be ensured.

In practice the said magnetic discs 19 may consist of annular magnets, and according to Fig. 7 it should then just be made sure that the central ring hole has a diameter smaller than the pin.

A possible further embodiment is that on a freely projecting end of a lock bolt there is mounted a mag¬ netic end cover cap, which will be held in the trans¬ verse direction by the bolt end itself, while in the longitudinal direction it will engage the side of the holding portion and thereby effectively prevent an unin- tensional rejection of the lock bolt at the occurrence of major rejection forces. Such a cover cap is easily placed, and it will not work loose at occurring vibrations.

For the different embodiments it will obviously be significant that the magnet portions are magnetized in relevant directions and altogether in a relevant manner to achieving the effective force of attraction, but in this instance this must be regarded as a question of applied professional know-how, for which reason these matters shall not be further dealt with here.