Locking device for a side or tail board of a truck

The locking device is provided with a jaw for receiving a swinging pin or trunnion, e.g. on the side or tail board of a truck or lorry, as well as with a bolt for the jaw opening. It also has a pivotably mounted claw movable by the bolt by means of a cotter gear and this claw grasps said pin as soon as it is in the pivoting region of the claw and forces it into the jaw. The bolt is advanced synchronously with the claw movement. The swinging pin is held by the bolt with supporting of the claw in the jaw.

FIELD OF THE INVENTION 
The invention relates to a locking device, e.g. for the tail board or side 
of a truck or lorry, with a stationary jaw for receiving a swinging or 
pendulum pin and with a locking bolt for the jaw. Importance is attached 
to easy manipulation, as well as to the actual locking function in 
connection with locking devices for the hinged or swinging tail boards of 
trucks, so that a device with a jaw is provided. On closing the tail board 
a pendulum or swinging pin fitted there passes into the vicinity of the 
jaw, where it is guided into a clearly defined end position. This guidance 
is necessary because the movable part with the swinging pin is often 
tilted with respect to the stationary part, alignment taking place 
forcibly by the jaw. 
BACKGROUND OF THE INVENTION 
DE-OS No. 27 40 573 discloses a locking device for the tail board or sides 
of trucks, which is provided with a swivel bolt, which is mounted in a 
housing by means of a pin. Within the housing is formed a force transfer 
zone, on which engages a two-armed angular pressure piece, which is also 
mounted by means of a pin. A manual rocking lever is articulated to one 
arm of the angular pressure piece. If a swinging pin passes in to the 
vicinity of the open swivel bolt, then by means of the manual rocking 
lever an operator deflects the angular pressure piece outwards acting on 
the compressive force transfer zone of the rocking lever. In order to 
reduce the frictional forces which occur, a roller with a pin is mounted 
in this zone on the rocking lever. As a result of the force transfer, the 
swinging pin is forced into the jaw. On opening the angular pressure piece 
engages on a cam extension on the swivel bolt, which is moved outwards. To 
ensure that the tail board pin is held in rattle-proof manner in the 
closed position, the swivel bolt is at least partly made from an elastic 
material. In addition, a slot is provided in which are located two disk 
springs, which press the elastic bolt zone onto the swivel pin. 
This locking device suffers from the disadvantage that all the closing a 
retaining forces acting on the swivel bolt have to be absorbed by the 
swivel bolt trunnion and the angular pressure piece trunnion. If one of 
these trunnions or a pivot bearing does not withstand this pressure, the 
trunnion jumps out of the jaw. There is also a risk of the swivel bolt 
breaking in the case of an excessive pressure of the trunnion, especially 
as it is slotted. With regards to the roller, it is to be expected that 
when transporting highly corrosive products, e.g. artificial fertilizers, 
residues will collect in the interior of the housing and the roller will 
become blocked through rust. 
DE-OS No. 29 32 763 discloses a locking means for hinge down and swing out 
tail boards of trucks, in which a locking rocker fulfills the function of 
bringing the swinging pin into the jaw and maintaining it therein. The 
manually operable locking rocker is articulated pivotably to a jaw part by 
means of two connecting rods. The locking rocker is held in the closed 
state by a safety catch. It is a disadvantage of this locking device that 
all forces have to be absorbed by the swivel bearing bolt, so that there 
is a risk of breakage in the case of higher forces. 
DE-OS No. 29 36 528 discloses a long-path locking means for hinge down and 
swing out tail boards, which is operable by means of a handle with a dead 
centre means. Upstream of a jaw is located a pivotable locking rocker, 
which is mounted by means of a bolt in the side walls of housing. In a 
further bolt, a toggle lever is articulated to the locking rocker and is 
connected by means of a knuckle joint to a second toggle lever also 
mounted in the housing wall with a bolt. This lever mechanism, which 
assumes a beyond dead centre position when the locking rocker is closed, 
is moved by means of a push rod suspended on the knuckle joint and leading 
to the handle, a lever action being exerted on the locking rocker by means 
of the toggle levers. It is a disadvantage of this locking device, that 
the reliability and operation are exclusively dependent on the bolts and 
if a single bolt fails it can no longer fulfill its function. In addition, 
all joints are naturally subject to wear, so that at least in the case of 
frequent operation and vehicle and swinging pin impacts the ball and 
socket joints can become deflected. This disadvantage cannot be 
compensated by the tensioning or clamping function of the beyond dead 
centre system, because such systems perform a setting movement. It is not 
possible to readjust the clearance of the articulated points, so that 
rattling occurs during all vehicle movements following a certain amount of 
wear, whereby such rattling must be avoided so as not to make the work 
place unduly noisy. 
Finally, DE-OS No. 29 40 671 discloses a locking device for walls, doors, 
flaps and reciprocally pivotable plates, in which the trunnion pin is held 
in the jaw by a displaceable bolt. The end of the bolt is constructed as a 
gripper for engaging in a corresponding recess on the trunnion pin. As 
soon as the bolt grips the trunnion pin, there is a centering and guidance 
in the jaw. The bolt is guided in a stable housing, which absorbs in 
large-area manner the forces from the swinging pin. This locking device 
admittedly functions reliably, but for trapping the swinging pin it has to 
be introduced a relatively long way into the jaw opening. 
OBJECT OF THE INVENTION 
The object of the invention, in the case of a locking device of the 
aforementioned type is to increase the trapping area on the jaw for the 
trunnion. 
SUMMARY OF THE INVENTION 
This object is achieved in that a pivotably mounted claw driven by the bolt 
in the direction of the jaw opening is provided which, when the bolt is 
open, is swung out from the jaw opening, which during the translatory 
movement of the bolt performs a swinging movement in the vicinity of the 
jaw opening and which when the bolt is closed is positioned upstream of 
the jaw. 
The function of this locking device is based on the fact that in a first 
phase the claw grips the swinging pin and brings the same into the 
engagement area of the bolt. In a second phase the claw supports the bolt 
when taking and aligning the same in the jaw. However, in the closed 
static state the claw is relieved by the bolt. The swinging pin is doubly 
secured both by the bolt and by the claw. This has the advantage that both 
the ease of operation and the reliability of the locking device is 
increased. According to an advantageous further development of the 
invention, the gear between the bolt and the claw is constructed as a 
cotter gear, comprising a cotter and a control bevel. This measure has the 
advantage that a compact construction of the locking device with small 
external dimensions is possible. If wear to the gear should make 
readjustment necessary, then reworking is easy, because only flat gear 
parts are affected. It is particularly advantageous if the cotter and 
precontrol bevel engage flat on one another with the bolt closed. The claw 
is reliably held in the closed position by this positive connection. It 
has also proved advantageous for the claw to have a centering and 
retaining bead for engaging in a corresponding slot-like recess on the 
swinging pin. This has the advantage that the trapping of said pin is 
facilitated. The centering and retaining bead corrects the movement 
sequence or position of the swinging pin in such a way that it is reliably 
grasped by the bolt. 
According to a preferred embodiment of the invention, the bolt head has a 
forked construction and the claw is mounted in the fork opening. As a 
result of this measure all the sliding faces of the claw are in contact 
with bolt faces, so that the frictional forces occurring there assist the 
movement of the claw. This arrangement also has the advantage that the 
fork parts engage on the swinging pin on either side of the claw and 
consequently any torsional forces from said pin cannot have any effect on 
the claw. 
According to a further development of the locking device, the bolt has a 
driver guided in a guideway in the claw. Driver and guideway bring about a 
precontrol of the movement sequence and have an assisting action on 
opening the locking device. Although when the locking device is positioned 
vertically an automatic opening of the claw is normally ensured by its own 
weight, this driver system makes it possible to overcome a temporary 
sticking of the claw, e.g. as a result of adhesive material being carried 
in the truck. 
The driver preferably comprises a cam and the guideway a slot, whose 
configuration is adapted to the superimposed pivoting and translatory 
movement of the claw or bolt. The curved configuration of the slot 
prevents the bolt and claw from passing into a dead centre. 
According to a further development of the invention a bolt-controlled catch 
is provided, which engages on the claw when the bolt is opened. This catch 
acts automatically, i.e. without any influence being necessary thereon by 
the locking device operator. The claw is held in the swung out position 
when the bolt is open, which prevents rattling in the case of a vehicle 
movement. 
According to an advantageous development, the catch comprises a pin 
provided with a chamfer and locating in the claw pivot axis for positive 
connection with a mating surface on the bolt. This catch is chracterized 
by its simple construction. 
According to an advantageous further development of the invention the bolt 
is guided in a bolt housing and the claw has a rounded end for a swinging 
or pivoting movement, with which it is mounted in a cavity formed from the 
housing bottom and a bolt recess. 
According to a further development of this mounting system, the claw is 
secured by means of a bolt member guided in its pivot axis and held in the 
bolt housing. 
According to a further, particularly advantageous development of the 
invention the bolt is provided with an extension arranged laterally with 
respect to the two fork parts and having a guidance surface for the 
trunnion and which can be moved as a lateral jaw boundary into the jaw. 
This guidance surface assists the alignment of the swinging pin in the 
jaw. This is brought about on the one hand through acting as a stop member 
for the swinging pin head and on the other hand in that through the bolt 
movement the swinging pin is actively moved into a position in which it 
can uniformly engage on the two fork parts. 
This extension is preferably guided in a three-wall guide web laterally 
terminating the jaw. This construction is able to absorb all the forces 
acting on the extension. It also has the advantage that the neck is 
stiffened by the side wall. In place of a free jaw part resting on a neck, 
there is consequently a partly closed jaw housing. This e.g. ensures that 
during a tilting movement when the tail board is placed on loose material 
or the like, the jaw is not forced upwards by the swinging pin or broken 
off. 
An undisturbed operation of the locking device is particularly obtained if 
a dirt channel passes along the bolt starting from the bearing opening, 
the cotter and the control bevel. As a result of these given shapes and 
chamfers, any dirt, such as e.g. sand penetrating from above into the bolt 
housing is removed downwards. This ensures that no dirt particles collect 
and the mobility of the locking device parts if not impaired. 
A simple and reliable operation of the locking device is obtained in that 
the bolt is connected by means of a push rod with a pivotable handle which 
is located in the dead centre position when the bolt is closed. If the 
length of the push rod is variable, the cotter gear can be readjusted by a 
slight lengthening of the push rod. 
According to an advantageous further development of the locking device, the 
bolt is longitudinally subdivided into two and the bolt part connected to 
the push rod is connected to the other bolt part in rotary manner, 
preferably about an angle of 90.degree.. This measure is particularly 
advantageous if the locking device is used for closing a tail board at the 
rear. The bolt and the handle to be swung out are then preferably 
positioned with an angle of , 90.degree., so that despite a rearwardly 
directed jaw the swinging movement of the handle takes place to the side. 
Therefore the operator does not have to pass into the folding area of the 
tail board and can instead operate the locking device in unimpeded manner 
from the side. It is also advantageous that in this way the dead centre 
system can be used unchanged for left-side and right-side housing forms. 
The connection point or junction of the two bolt parts is preferably within 
the housing, so that it is protected from any action. 
According to a preferred development of the invention, the housing height 
is no more than 40 mm. This has the advantage that for a given maximum 
vehicle width of e.g. 2.50 m and with a two-sided arrangement of the 
locking device, the available loading width can be utilized up to an 
interior dimension of 2.42 m. For example, this loading width makes it 
possible to load in juxtaposed manner two so-called Euro-pallets.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
As is shown in FIG. 1, the locking device is fitted in stationary manner to 
a stanchion 8 in a vertical arrangement. In the represented embodiment, it 
is a left-sided part, which is apparent from a left-sided, completely 
closed housing 1, so that a jaw 2 for a swinging pin 10 is bounded on the 
left-hand side. A corresponding right-sided construction of the locking 
device differs in that the jaw 2 is terminated by housing 1 on the 
right-hand side and is open on the left-hand side. The swinging pin 10 is 
fitted to a side or tail board 12. It has an all-round recess 11 with 
chamfered side faces, which aid the trapping by a claw 13 and the 
centering and alignment in jaw 2. 
In housing 1 is guided a bolt 3, which is connected by means of a 
length-adjustable thrust arm 4 with a beyond dead centre operating system 
9. The length of thrust arm 4 is brought about by means of a threaded rod 
14, which is connected on the one hand to a fork 15 on bolt 3 and on the 
other hand by means of a further fork 16 to a pivotably articulated handle 
7. Handle 7 is held in articulated manner in a bearing 6 by means of a 
lever 17. 
For closing or locking the device, handle 7 is pivoted in the direction of 
the arrow, so that it assumes the position shown in FIG. 2. During this 
pivoting movement, bolt 3 is moved upwards into jaw 2, whilst 
synchronously thereto claw 13 performs a pivoting movement out of the 
swung out position shown in FIG. 1 until it is positioned upstream of jaw 
2 with the bolt closed. Tail board 12 and swinging pin 10 are not shown in 
FIG. 2 in order not to overburden the drawing. As will be shown 
hereinafter one of the functions of claw 13 is to grasp the swinging pin 
10, as soon as it is in its swinging or pivoting range and press it into 
jaw 2. 
FIG. 3 diagrammatically shows the arrangement of bolt 3 and claw 13 in 
housing 1, housing 1 and bolt 2 being partly cut away along their median 
longitudinal axes. 
Housing 1 comprises a closed base plate 19, two side walls and a cover 
plate 20. One side wall is provided with a downwardly tapering opening 21 
for forming the jaw. The other side wall is contructed as a guide web 22 
in the vicinity of jaw 2. End face 23 of housing 1 forms the upper 
boundary of jaw 2. In the vicinity of jaw 2 a centering bead 24 is formed 
centrally on base plate 19. 
The bolt 3 provided at its rear end with a fork connection 25 comprises a 
block part 26 with a rectangular cross-section, whose free end (bolt head) 
27 has a fork-like construction, claw 13 being guided in the central fork 
opening. Bolt head 27 has an extension 28 guided laterally along guide web 
22 with a guide face directed into the jaw for the swinging pin. Behind 
the fork opening bolt 3 is also provided with a chamfer which, as will be 
shown hereinafter, acts as a cotter 30 for claw 13. 
The back of claw 13 serves as a control bevel 31 which, in conjunction with 
cotter 30 forms a cotter gear. The bearing end of the claw is rounded, so 
that during a pivoting movement it rolls on the housing bottom 19. it is 
laterally guided by the two fork parts 29. In the represented embodiment, 
claw 13 is pivotably articulated by means of a bolt member 33 between the 
housing walls. A slot 34 is provided laterally on claw 13 for the 
precontrol of the cotter gear and in it engages a cam 35 from a fork part 
29. Around the pivot axis of claw 13 is laterally formed a cam 37 provided 
with a chamfer 36. When bolt 3 is open, i.e. when the claw 13 is 
completely swung out in accordance with FIG. 3, a mating surface 38 formed 
on bolt 3 engages positively on chamfer 36. Chamfer 36 and mating surface 
38 together form a catch controlled by bolt 3 and which engages for fixing 
claw 13. 
FIG. 4 is a plan view claw 13 in the direction of arrow IV. It is clearly 
possible to see the control bevel 31 and cam 37, whilst chamfer 36 is 
concealed as a result of the chosen view. 
Further details of claw 13 will now be described relative to FIG. 5. The 
free end of the claw is provided with a centering and retaining bead 40 as 
a counter part to centering bead 24 in housing 1 and said bead 40 runs in 
a concave recess. On the same side is provided a projection 41 for 
engaging with a driver 53 on bolt 3, as shown in FIG. 6. The guide for 
bolt member 33 carries reference numeral 39. In the example chosen in FIG. 
5 the slot 34 has a curved configuration chosen in such a way that it is 
adapted to the superimposed pivoting and translatory movement of claw 13 
or bolt 3. In a lower region where cam 37 is located when claw 13 is swung 
out, slot 34 is slightly curved to ensure that bolt 3 and claw 13 do not 
pass into a dead centre position here. The configuration of slot 34 is 
such that it has an angle of inclination, even when claw 13 is swung out 
perpendicularly. 
FIG. 6 is a view of bolt 3 from the direction of arrow VI in FIG. 3. FIG. 6 
clearly shows fork part 29 with the interposed fork opening 42 for 
receiving claw 13. With respect to block part 26, the fork opening 42 is 
bounded by the sloping face of cotter 30. It passes into a recess 43, 
which runs in slot-like manner along the entire block part 26. In this way 
a channel is formed along the entire bolt 3 and this channel serves to 
remove downwards dirt particles which have penetrated the housing via jaw 
2. The mating surface 38 of the catch is formed on a step-like shoulder of 
a fork part 29 following onto driver 41. FIG. 6 also shows how cam 35 
projects into fork opening 42. 
In order to illustrate the function of extension 28, the head of swinging 
pin 10 is diagrammatically shown in an exaggerated tilted position. As a 
result of a longitudinal movement of bolt 3, head 10 is subject to a 
tangential force, which aligns it in jaw 2. This alignment is assisted by 
the fact that a guidance face 44 on the side of extension 28 slides along 
the end face of head 10. 
FIG. 7 shows the bolt in a longitudinal section along the centre line in a 
view according to arrow VII in FIG. 6. Along its end face 50, extension 28 
is slightly chamfered in the direction of the housing base plate, so that 
on grasping the swinging pin the forcing into the jaw is assisted. The two 
fork parts 29 pass out into grippers 48, whilst adapting to the swinging 
pin cross-section. A bolt recess 49 is provided for pin 37. 
FIGS. 8, 9 and 10 show the housing 1 and bolt 3 in partly cutaway form, in 
order to cearly reproduce essential details of the locking device. 
By means of FIGS. 1 to 8, the function of the locking device will now be 
described. When the bolt 3 is open, the catch comprising chamfer 36 and 
mating surface 38 hold the claw 13 positively in the supported position. 
On moving the bolt, contact is broken between chamfer 36 and mating 
surface 38, so that a pivoting movement of the claw 13 in the direction of 
jaw 2 is not prevented. Simultaneously cam 35 presses against the side 
wall slot 34 and controls a movement of claw 13. In addition, the cotter 
gear moves claw 13, in that the tip of cotter 30 presses on control bevel 
31. During this movement pin 37 in a recess 49 of bolt 3 is out of contact 
with the latter. If there is a swinging pin 10 in the pivoting region of 
claw 13, then pin 10 is forced into jaw 2. The lateral alignment of 
swinging pin 10 is brought about in that the centering and retaining bead 
40 engages in the adapted recess 11 (FIG. 1) of said pin. The vertical 
alignment of the swinging pin 10 takes if comes into contact with the 
extension 28 moving laterally into the jaw. FIG. 8 e.g. shows the 
situation in which the bolt 3 has covered roughly half the bolt travel. 
The swinging pin 10 is immediately in front of the centering bead 24. 
Extension 28 which is chamfered rearwards in the direction base plate 19 
is advanced roughly up to the centre line of pin 10. Fork part 29 is still 
out of contact with pin 10. 
FIG. 9 finally shows a cross-section through the locking device in the 
closed state. Cotter 30 is so far advanced in this position that the 
cotter face is in whole-area positive engagement with the control bevel 
31. During the preceding movement following on to the situation according 
to FIG. 8, the fork parts 29 penetrate jaw 2 and engage with the swinging 
pin. In the closed position shown in FIG. 9 the cotter 30 completely 
arrests claw 13. The swinging pin, which is not shown for reasons of 
clarity, is on the one hand positively secured by the fork parts 29 at 
both ends of claw 13 and also by bolt 3, all the forces acting on the claw 
being transferred by means of cotter 30 to bolt 3 or the housing. 
FIG. 10 shows the arrangement of fork parts 29 and claw 13 on swinging pin 
10. It can be gathered from FIG. 10 that the extension 28 is mounted in 
guide web 22 and consequently contributes to stability and the absorption 
of forces. The forces acting on bolt 3 are consequently absorbed by the 
housing 1 in conjunction with extension 28. 
On opening the locking device, when bolt 3 is retracted, The surface of 
cotter 30 is immediately disengaged from the control bevel 31, so that 
claw 13 is immediately freed. In the case of a horizontal arrangement, it 
is swung outwards by its own weight. In addition, the swinging out is 
assisted by cam 35 and slot 34. The forcibly controlled return link brings 
the claw back into the inital position of FIG. 3, in which it is held in 
clearance-free manner by the catch. 
FIG. 10 shows the bolt 3 split longitudinally. The bolt part 51 connected 
to the push rod is rotated with respect to the other bolt part 52 by 
90.degree. compared with the arrangements shown in the other drawings. 
Thus, fork 15 together with the complete actuating means 9 (FIGS. 1 and 2) 
can also be rotated by 90.degree.. The two bolt parts are detachably 
interconnected by means of a screw joint 46. By loosening this screw joint 
46, it is possible at all times and without difficulty to reciprocally 
turn the two bolt parts. The junction is concealed in housing 1.