Guidable bogie truck for mobile cranes

A guidable bogie truck for a mobile crane, such as a mobile gantry crane, includes a frame having longitudinal supports; a pair of wheel mechanisms connected to one end of the frame and a pair of wheel mechanisms connected to the opposite end of the frame, one of the pairs of wheel mechanisms being connected to pivotable axles which allows the associated pair of wheel mechanisms to constitute guide wheel mechanisms; four support legs movably connected to the frame; lifting devices connected to each of the four support legs to extend them downwardly to contact the ground and support the frame or to retract them upwardly towards the frame; wheel drive motors for turning the wheel mechanisms; adjustment motors for pivoting the pivotable wheel axles; and a common control device for controlling the operation of the bogie truck parts. A control panel on the bogie truck includes a shift lever and direction-setting parts which are connected to the common control device to allow the operator to suitably determine the operation of the common control device and thus the bogie truck.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a guidable bogie truck, and especially a 
guidable bogie truck which can support a mobile crane. 
2. The Prior Art 
Large and heavy gantry cranes, which are, for example, used to load and 
unload goods from ships in harbors, are frequently constructed to move 
along guide rails on the ground to enable them to be moved from one work 
site to another by operators who have little experience. However, because 
the guide rails will be fixed in position, these gantry cranes are limited 
as to the different sites to which they can be moved, and in addition the 
guide rail systems are in and of themselves expensive and time consuming 
to construct and maintain. On the other hand, although mobile gantry 
cranes which can move independently of guide rails will have a much 
greater versatility, the opportunities for accidents and/or damage to the 
crane structures is very great, and only very experienced operators can be 
used to control their movements. 
At the same time, however, at many locations (especially in underdeveloped 
countries) the availability of experienced operators may be very limited 
and the terrain around the freight loading and unloading sites may be in 
bad condition. Thus mobile gantry cranes which are movable independently 
of guide rail systems, and which would be of the needed size, although 
economically advantageous to use, cannot be employed. 
It is an object of the present invention to provide a guidable bogie truck 
for mobile cranes, especially mobile gantry cranes, which can be easily 
operated by unskilled (although necessarily conscientious) operators, such 
that the mobile cranes can be successfully used even at sites which may be 
in bad condition. 
SUMMARY OF THE INVENTION 
According to the present invention, the guidable bogie truck includes a 
frame; two pairs of wheel means, one pair being connected to the front end 
of the frame and the other pair to its back end, the pair of wheel means 
on at least one of its ends being connected to pivotable wheel axles which 
can pivot to guide the bogie truck; four support legs, each support leg 
being movably connected to the frame near a respective wheel means and 
each including a footplate for contact with the ground; lifting devices 
connected to each of the support legs to extend the associated support leg 
towards the ground or retract it upwardly towards the frame; at least one 
adjustment motor to cause the pivotable wheel axles to pivot; at least one 
wheel drive mechanism to turn at least one pair of wheel means; and a 
common control device for controlling the operation of the essential bogie 
truck parts. 
The advantages obtainable with the invention are in particular the fact 
that only direction-setting parts need be actuated when the bogie truck is 
stopped, and that all steps thereafter required occur automatically. 
The invention will now be better understood by reference to the 
accompanying drawings taken in conjunction with the following discussion.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
One embodiment of a guidable bogie truck for a mobile gantry crane 
according to the present invention is schematically shown in FIGS. 1 and 
2, FIG. 1 showing a side view and FIG. 2 showing a front view. The gantry 
crane 1, which includes a platform 2 resting on two pairs of legs 3a, 3b 
for the operative crane structure (not shown), is mounted on two identical 
and parallel longitudinal supports 5a, 5b of a rigid bogie truck frame 4. 
The end parts of the longitudinal supports 5a, 5b extend beyond both of 
the corresponding sides of portal 1. FIG. 3 shows a top view of one of the 
longitudinal supports 5a. 
Both of the longitudinal supports 5a, 5b are constructed as solid-wall box 
girders and thus are very strong. As indicated in FIG. 5, they may, for 
example, be formed of fixed I beams. Corresponding first ends of the 
longitudinal supports 5a, 5b are closed by massive closure plates 6 which 
are each formed to include a horizontal, rigid wheel axle 7 so as to 
extend in the longitudinal direction of the associated support, whereas 
the second ends of the longitudinal supports connect to upwardly extending 
swan-neck pieces 8a, 8b located beyond the end of the portal 1. These 
swan-neck pieces are constructed in the same manner as the longitudinal 
supports themselves, and each carries a respective rotatable, vertical 
axle 9a, 9b. Each axle is respectively coupled to a servomotor SMa, SMb at 
its upper, free end and to a horizontal pivotable wheel axle 10a, 10b at 
its lower end. 
Each of the two horizontal, rigid wheel axles 7 and the two horizontal, 
pivotable wheel axles 10a, 10b form respective wheel pairs 19a, 19b and 
27a, 27b on wheel suspensions in the embodiment shown in FIGS. 1 to 3. The 
wheel suspensions are of a conventional type and preferably have 
respective independent axles 20, 28. Usually the bogie truck travels with 
the wheel pairs 27a, 27b, which are mounted on pivotable wheel axles 10a, 
10b, functioning as front wheels and with the wheel pairs 19a, 19b, which 
are mounted on rigid wheel axles 7, functioning as rear wheels. The front 
wheel pairs 27a, 27b are appropriately moved in order to guide (steer) the 
bogie truck. In order to move pivotable wheel axles 10a, 10b with vertical 
axles 9a, 9b, a hollow cylindrical intermediary piece 11 is coaxially 
fastened, e.g. welded, to the respective vertical axles 9a, 9b on each 
longitudinal support 5a, 5b on the underside of swan-neck piece 8a, 8b. 
This intermediary piece 11 carries respective concentric, horizontal disks 
12a, 12b permanently connected to it as a rigid bearing part for 
respective rotary concentric disks 16a, 16b located thereunder. The two 
rotary disks are permanently connected to vertical axles 9a, 9b and each 
one has a pair of pillow blocks 18, 18' on its underside in which 
pivotable wheel axles 10a, 10b are mounted. 
An all-wheel drive with a wheel drive device M.sub.V for each front wheel 
27 and a wheel drive device M.sub.H for each rear wheel 19 is provided in 
the bogie truck shown in FIGS. 1 to 3. The wheel drive devices M.sub.V, 
M.sub.H are preferably hydraulic devices which are associated with a 
common pump aggregate 29, as is well-known in the drive art. 
Brake devices 21, indicated by dotted lines in FIGS. 2 and 3, are 
associated with rear wheels 19, 19' located on rigid wheel axles 7 of 
longitudinal supports 5a, 5b. Brake devices 21 are constructed so that 
they block rear wheels 19, 19' when at rest and can only be released by a 
power producer 22. Power producers 22 are likewise preferably hydraulic 
devices. 
The two longitudinal supports 5a, 5b are provided with conventional support 
legs 30 which are positioned on the longitudinal supports 5a, 5b near the 
joining points of portal legs 3a, 3b. These support legs 30 can be 
extended and retracted by means of individual lifting devices 32. Both the 
support legs 30, which are equipped with footplates 31, and the associated 
lifting devices 32, which are preferably hydraulic, are positioned and 
arranged in such a way that when they are completely extended, wheels 19, 
27 of the bogie truck are completely raised off of the ground. 
A control panel 33 which is readily accessible to and easy to operate by 
the crane operator is located on the swan-neck piece 8a of the one 
longitudinal support 5a. The control panel 33 functions to guide the bogie 
truck. The shifting and setting parts of this control panel, as well as in 
particular a shifting part 34, which is preferably constructed as a guide 
lever for guiding wheel drive devices M.sub.V, M.sub.H to a desired 
direction of travel and travel speed, and direction-setting parts 35 for 
selecting pivot positions for the pivotable wheel axles 10a, 10b, act on a 
guide device SE. As will be described in more detail later, guide device 
SE is set up so that when the shifting and setting parts of control panel 
33 are actuated, even under difficult local conditions, a safe moving and 
setting-up of the bogie truck are assured by basically automatic guide 
processes for the power producer 22 of the brake devices 21 and for 
lifting devices 32 associated with the support legs 30, as well as for the 
devices for moving pivotable wheel axles 10a, 10b. The latter are treated 
in more detail in conjunction with FIGS. 4 to 8. 
In order to execute a circular path, pivotable wheel axles 10a, 10b on the 
bogie truck must, as is known, be set so that the respective geometric 
axes of rotation a, b, c of the wheels is achieved. Wheel pairs of the 
bogie truck intersect each other approximately in the center of the circle 
(rotational point D) as is illustrated schematically in FIG. 4 for a left 
curve with curvature radius r to be traveled by the previously described 
bogie truck. When pivotable wheel axles 10a, 10b are set to follow a 
curve, the wheel pair on the inside of the curve should be set at an angle 
.alpha. which is greater than the adjustment angle .beta. of the wheel 
pair on the outside of the curve. Adjustment (setting) angles .alpha. and 
.beta. for pivotable wheel axles 10a, 10b can be calculated by a computer 
from the separations of the wheel pairs from each other (these separations 
are fixed for a given bogie truck); from any selected curve curvature 
radius r; from any pivot process selected, such as forward or reverse 
travel; and from whether rotary point D is on the side of the one 
longitudinal support 5a, on the side of the other longitudinal support 5b, 
or whether the bogie truck is to pivot in place about rotary point D' 
located in the middle between the rear wheel pairs 19, 19' on their common 
axis of rotation C. Pivotable wheel axles 10a, 10b can then be set 
appropriately by vertical axles 9a, 9b coupled to positioning motors SMa, 
SMb using the values calculated for adjustment angles .alpha. and .beta. 
as theoretical values for guiding adjustment motors SMa and SMb. When the 
bogie truck is guided in this manner, the driver should estimate the 
radius of curvature for each arc to be traveled, which would necessitate 
frequent connections in the case of an inexperienced crane operator, for 
which the bogie truck would have to be halted. Changes in place of a large 
and heavy gantry crane are usually executed very slowly, so that a 
considerable amount of time spent in traveling an arc is frequently 
acceptable, and the arc can be traveled, by linking together short, 
straight path sections. Only three settings are needed for such a mode of 
travel for each pivotable wheel axle 10a, 10b: straight ahead (0.degree.) 
and stationary pivoting to the right and to the left (90.degree. r and 
90.degree. l), and the control panel 33 (FIG. 3) could have only three 
correspondingly designated buttons as direction-setting parts 35 for 
entering the theoretical values for adjusting adjustment motors SMa and 
SMb into guide device SE. The crane operator need have no experience or 
practice for such an extremely simple operation, and any movement of the 
bogie truck can be accomplished without damage or accident, given 
sufficient caution and care. 
The time needed for describing an arc can be shortened without placing 
great demands on the crane operator by providing a few intermediate 
positions for pivotable wheel axles 10a, 10b between the extreme positions 
of straight ahead (0.degree., curvature radius .infin.) and stationary 
pivoting (90.degree., curvature radius equal to axial wheel interval on 
the longitudinal support), such as, for example, 15.degree. for a large 
curvature radius, 30.degree. for an average one and 45.degree. for a small 
curvature radius. The curvature radii in relation to the length of the 
bogie truck are easy to estimate by the crane operator, and only slight 
corrections, if any, need be performed by pivoting in place when 
describing an arc after actuation of the appropriate direction-setting 
part 35. Such a setting device with a simple construction is schematically 
represented in FIGS. 5 and 6. 
FIG. 5 shows a front view of the front wheels 27a, 27'a of a longitudinal 
support 5a and shows swan-neck piece 8ain section with hollow cylindrical 
intermediary piece 11, as well as disk 12a which is permanently connected 
to intermediary piece 11. Rotary disk 16a, which carries pillow blocks 18, 
18' for the pivotable, horizontal wheel axle 10a, rests in an easily 
rotatable fashion on the underside of disk 12a over a crown of balls or 
rollers 15. The lower end of vertical axle 9a runs through a control 
opening 13 in disk 12a and is permanently connected to rotary disk 16a. 
Vertical axle 9a, coupled to adjustment motor SMa, carries a horizontal 
cam disk 40a on its upper end which, as FIG. 6 shows, is constructed as a 
complete circle with only one notch 41 or only one cam. When vertical axle 
9a turns, cam disk 40a turns too, and the particular position of notch 41 
in relation to a reference point on swan-neck piece 8 a indicates the 
setting angle of pivotable wheel axle 10a. In FIG. 6 straight ahead travel 
is indicated by arrow 42, and the position of notch 41 shown there 
indicates that pivotable wheel axle 10a is in the 0.degree. setting for 
traveling straight ahead. Addressible signal transmitters 43.sub.o, 
43.sub.11 -43.sub.41 43.sub.1r -43.sub.4r are permanently fixed around cam 
disk 40a on swan-neck piece 8a in the 0.degree. position for 
straight-ahead travel and in the angular positions calculated for right 
and left arcs in relation to given nominal settings such as 15.degree., 
30.degree., 45.degree. and 90.degree.. These signal transmitters scan cam 
disk 40a, e.g. with tappets 44, each of which emits an actual value signal 
if its tappet 44 senses notch 41 of cam disk 40a. The setting device on 
the other longitudinal support 5b is constructed in the same manner; 
however, the position angles for the signal transmitters for left arcing 
(turning) and right arcing are interchanged, since in the case of 
longitudinal support 5b the front wheel pair 27b is on the inside of the 
curve for a left turn (arc) and is on the outside for a right turn. 
Individual direction-setting parts 35 are provided on control panel 33 for 
the provided settings of 0.degree., 15.degree. . . . 90.degree. for 
turning left and 15.degree. . . . 90.degree. for turning right. The signal 
transmitters 43 of the two setting devices associated with each 
direction-setting part 35 are selected over guide device SE by the 
actuated part 35. Guide device SE produces guide signals for the two 
adjustment motors SMa and SMb from the existing (fixed) actual value 
signal and the selection signal (theoretical value signal) obtained when a 
direction-setting part 35 is actuated, whereupon adjustment motors SMa and 
SMb turn in the proper direction of rotation until notch 41 of each cam 
disk 40a, 40b reaches the selected signal transmitter 43. Such a guiding 
of motors occurs frequently in the art, e.g., the guiding of elevators, so 
that many circuits, even simple ones, are known for this purpose, and the 
details of these circuits will not be discussed further. 
When pivotable wheel axles 10a, 10b are adjusted, their wheels or wheel 
pairs 27a, 27b are always raised off the ground by the extension of at 
least the front support legs 30 on the longitudinal supports 5a, 5b. After 
pivotable wheel axles 10a, 10b have been set, vertical axles 9a, 9b are 
fixed so firmly in their particular rotated position that the setting is 
maintained even if the bogie truck runs against an obstacle. 
FIGS. 7 and 8 show a preferred, simple stop device for front wheel pair 27a 
in FIG. 5. For stopping vertical axle 9a, disk 12a, which is fastened 
firmly to intermediary piece 11, and rotary disk 16 are connected together 
so that they cannot rotate by means of a vertical bolt 49 in the 
particular rotated position. In the stop device 45 shown, bolt 49 is the 
piston rod of a single-acting hydrocylinder 46, the piston 48 of which is 
pressed by spring 47 into the end position in which bolt 49 (the piston 
rod) is inserted in the particular rotated position of vertical axle 9a in 
mutually aligned boreholes 14 and 17 in disk 12a and in rotary disk 16a, 
thus firmly holding rotary disk 16a to the disk 12a which is firmly 
attached to intermediary piece 11. Hydrocylinder 46 can be fastened to 
intermediary piece 11 above disk 12a or, as is shown in the drawing, it 
can be located on one of the pillow blocks 18, 18' which carry pivotable 
wheel axle 10a. The disk near hydrocylinder 46 has a single borehole 
through which bolt 49 extends, and the disk further away from 
hydrocylinder 46 has a number of boreholes corresponding to the settings 
provided which are positioned in the same angular positions as the signal 
transmitters (FIG. 6) and into which bolt 49 engages in the particular 
rotated position. Thus, in the case of hydrocylinder 46 fastened to pillow 
block 18 rotary disk 16a has only one borehole 17 and disk 12a, which is 
fixed to intermediary piece 11 and is shown in a top view in FIG. 7, has 
boreholes 14.sub.o, 14.sub.11 -14.sub.41, 14.sub.1r -14.sub.4r 
corresponding to the provided settings for straight ahead, left turn and 
right turn. 
The schematic diagram in FIG. 9 shows the hydraulic devices of the bogie 
truck with their oil circulation systems and the control circuits affected 
by the shifting and setting parts of control panel 33. 
Wheel drive devices M.sub.Va, M.sub.Vb, M.sub.Ha, M.sub.Hb for the front 
and rear wheels or wheel pairs 27a, 27b, 19a, 19b are hydromotors 50 which 
are equipped with, e.g., electro-hydraulic directional control valves 51 
as setting members. These hydromotors are supplied with oil under pressure 
from a regulatable hydropump 52 of pump aggregate 29, which is adjustable 
by means of control lever 34 on control panel 33, via pressure oil lines 
53 and are connected to pump aggregate 29 via oil return lines 54. When 
control lever 34 is moved out of its neutral position in the one direction 
v for forward travel and in the other direction z for reverse travel, 
control signals are sent via signal lines 55 to directional control valves 
51 which cause valves 51 to move out of their neutral center positions for 
turning hydromotors 50 in the one or the other direction of turn. Such 
hydraulic drive systems are conventional, so that further details are 
unnecessary. 
The other hydraulic devices of the bogie truck, that is, the hydraulic 
pivot motors 56 with input-side electrohydraulic directional control 
valves 57, which motors are provided as adjusting motors SMa and SMb for 
moving vertical axles 9a and 9b; the single-acting hydrocylinders 46 with 
electro-hydraulic directional control valves 58, which cylinders are used 
in stop devices 45a, 45b for stopping vertical axles 9a, 9b; the 
double-acting hydrocylinders 60 with directional control valves 61 which 
function as lifting devices 32 for support legs 30; and the single-acting 
hydrocylinders 24 with electrohydraulic directional control valves, which 
are used as power producers 22 for releasing braking devices 21 which 
block rear wheels or wheel pairs 19a, 19b under the action of springs 23, 
are all connected to a separate oil circulation system in which they are 
supplied with oil under pressure from a constant pump 65 of pump aggregate 
29 via pressure oil lines 66, and in which oil from the hydraulic devices 
is returned through oil return lines 67 back to pump aggregate 29. 
Electro-hydraulic directional control valves 25 (of power producers 22 for 
braking devices 21), 57 (of adjusting motors SMa, SMb), 58 (of the stop 
devices 45a, 45b) and 61 (of the lifting devices 32 for support legs 30) 
are connected to guide device SE via control signal lines 68, 69, 70, 71 
which are indicated in FIG. 9 by simple solid lines. Indicating signal 
transmitters are associated with power producers 22, stop devices 45a, 45b 
and lifting devices 32, are connected to control device SE by indicator 
signal lines shown in FIG. 9 in simple dotted lines and indicate the 
current operational states of the devices to the control device with 
appropriate signals. A limit switch, for example, actuated by the piston 
rod of hydrocylinder 24, is provided in each braking device 21 as a 
"blocking--indicating signal transmitter" 26. This limit switch indicates, 
via indicating signal line 72, to control device SE whether braking device 
21 is set for blocking or for release. Likewise, in stop devices 45a, 45b 
the "stop-indicating signal transmitters" 59 can be limit switches 
actuated by bolts 49 (FIG. 8), which switches are connected via indicating 
signal lines 73 to control device SE and emit corresponding signals when 
vertical axles 9a, 9b are stopped or released. The "lift-indicating signal 
transmitters" 62 present in lifting devices 32 for support legs 30 are 
advantageously limit switch combinations, which are actuated by the piston 
rod of hydrocylinder 60 and/or, e.g., by footplate 31. These transmitters 
62 emit indicating signals via indicating signal lines 74 to control 
device SE at least for a fully retracted support leg and for a fully 
extended support leg. Other signal lines 75 connect control device SE to 
the signal transmitters required for setting vertical axles 9a, 9b (FIGS. 
5, 6), which transmitters are now shown in FIG. 9 for the sake of clarity. 
All of the above-mentioned devices of the bogie truck are turned on by 
actuating main switch 37, which is on control panel 33 and is preferably a 
lock switch. However, control device SE is set up in such a manner that an 
actuation of control lever 34 and of direction-setting parts 35, which 
have symbols for the various wheel positions in FIG. 9 for the sake of 
differentiation, only becomes effective when a safety switch constructed 
as a key is actuated simultaneously with the other hand. 
In order to orient the erected bogie truck into a horizontal position so as 
to obtain an even load, hand-actuated switching parts 63, 64 are 
associated with each directional control valve 61 of lifting devices 32 
for support legs 30. Support legs 30 can be extended and retracted as 
desired with these switching parts independently of the control device SE. 
An actuation of these lifting-switching parts 63, 64 only becomes 
effective, however, when main switch 37 and a switching part 36 for lift 
release, both of which are on control panel 33, have been actuated. 
A logical electrical circuit for the one part of control device SE 
associated with the devices of the one longitudinal support 5b is shown in 
schematic fashion in FIGS. 10 and 11 in order to explain the control 
processes commenced with the actuation of switching part 34 for 
controlling wheel drive devices M.sub.Va, M.sub.Mb, M.sub.Ha, M.sub.Hb and 
of direction-setting parts 35 for controlling adjusting motors SMa, SMb. 
The other part of control device SE associated with the devices of the 
other longitudinal support 5a is constructed correspondingly. Note, 
however, that only a few switching elements which are useful for 
illustrating the method of operation are entered in FIGS. 10 and 11, and 
that the circuit shown is in no way representative for a professional 
construction. 
For adjusting vertical axle 9b, a theoretical value signal is entered into 
control device SE by actuating one of the direction setting parts 
35.sub.o, 35.sub.1l. . . 35.sub.nl and 35.sub.1r . . . 35.sub.nr of 
control panel 33. This is illustrated in FIG. 10 by variable resistors 76 
connected to direction-setting parts 35 and set at resistance values which 
are individual for them. Direction-setting parts 35 are preferably touch 
contacts, and when one of the direction-setting parts 35 is actuated in 
the circuit arrangement shown, an electronic switch 77 is cut in by a 
cut-in signal onto one of its input lines 78, over which switch voltage is 
put on signal transmitters 43 which are shown in FIGS. 5 and 6 and which 
scan cam disk 40, so that control device SE receives an actual value 
signal for the actual setting of vertical axle 9b. A potentiometer 40'b is 
shown in FIG. 10 instead of signal transmitters 43 and cam disk 40 for the 
sake of simplicity. Control device SE contains a comparator 80 which 
compares the entered theoretical value signal with the actual value signal 
and, depending on whether the entered theoretical value is greater or 
smaller than the actual value, emits a control signal onto one or the 
other of its two output lines 81, 82 connected to electro-hydraulic 
directional control valve 57 of pivot motor 56. This signal moves valve 57 
out of neutral position into one or the other operating position, and 
pivot motor 56 begins to turn in the direction in question. In 
compensation, when the actual value is equal to the entered theoretical 
value, comparator 80 puts a cut-out signal on another input line 79 of 
electronic switch 77, which signal turns off (cuts out) switch 77. 
Control device SE is set up in such a manner that the actuation of a 
direction-setting part 35 is only effective if at least the support legs 
30 located near pivotable wheel axles 10a, 10b (FIGS. 103) have been 
placed into their extended position by means of their lifting devices 32, 
in which position guidable wheels or wheel pairs 27a, 27b are raised off 
the ground, and stop devices 45 (FIGS. 7, 8) have released a turning of 
vertical axles 9a, 9b, and, finally, no wheel drive device is engaged. For 
this purpose the two output lines 81 and 82 of comparator 80 in the 
circuit shown are each connected over an AND circuit 83 and 84 to 
directional control valve 57, each of which has a second input connected 
to the limit switch used as a stop-indicating signal transmitter 59 of 
stop device 45b, and (each of which has) a third input connected to the 
limit switch of lifting device 32 present as light-indicating signal 
transmitter 62. The second and the third inputs of the two AND circuits 83 
and 84 receive L signals from indicating signal transmitters 59 and 62 
when stop device 45b has been put out of operation and support leg 30 has 
been completely extended by lifting device 32. 
In stop device 45b the two gate terminals 58.sub.1, 58.sub.2 of 
electro-hydraulic directional control valve 58 are each connected to an 
AND circuit 85, 86 with two inputs. The one AND circuit 85 receives an L 
signal on one input when electronic switch 77 is cut in, and it only 
receives an O signal on the other input from stopping signal transmitter 
59 when the connection of disk 12b and rotary disk 16b by means of bolt 49 
has been completely broken. When vertical axle 9b is stopped and 
electronic switch 77 is cut in, this AND circuit puts an L signal on gate 
terminal 58.sub.1 of directional control valve 58, which moves valve 58 
out of its neutral position into the position which connects hydrocylinder 
46 to the pressure oil line 66 and initiates the stopping by means of 
hydrocylinder 46. When the stopping has been completely released, the 
input of AND circuit 85 connected to stopping signal transmitter 59 
(contact 59a) receives an O signal, whereupon directional control valve 58 
returns to its neutral position. The other AND circuit 86 receives the 
cut-out signal emitted from comparator 80 during compensation to 
electronic switch 77 on one input as L signal and only receives an O 
signal on the other input from stopping signal transmitter 59 (contact 
59b) if the connection of disk 12b and of rotary disk 16b by bolt 49 has 
been properly established. After the moving of vertical axle 9b has been 
accomplished and indicated by the cut-out signal emitted by comparator 80, 
AND circuit 86 puts an L signal on gate terminal 582 of directional 
control valve 58 which moves valve 58 out of its neutral position into the 
position which connects hydrocylinder 46 to the oil return line 67 and 
presses bolt 49 via spring 47 into the stop position. When the stopping of 
vertical axle 9b has been properly established, the input of AND circuit 
86 connected to stopping signal transmitter 59 (contact 59b) receives an O 
signal and directional control valve 58 returns to its neutral position. 
In the front lifting device 32.sub.v, each of the two gate terminals 
61.sub.1 and 61.sub.2 of electro-hydraulic directional control valve 61 is 
connected to an AND circuit 87, 88 with two inputs. The one AND circuit 87 
receives an L signal on one input when electronic switch 77 is cut in, and 
only receives an O signal on the other input from lift indicating signal 
transmitter 62 (contact 62a) if support leg 30 is completely extended. 
When electronic switch 77 is cut in and support leg 30 is not completely 
extended, this AND circuit 87 puts an L signal on gate terminal 61.sub.1 
of directional control valve 61 which moves valve 61 from its neutral 
position into its work position, in which the connected hydrocylinder 60 
is connected to pressure oil line 66 and to oil return line 67 for 
extending support leg 30. When support leg 30 is completely extended 
(contact 62a), the signal on the other input of AND circuit 87 changes 
from L to 0 and directional control valve 61 returns to its neutral 
position while support leg 30 remains extended. 
L signals as control signals for electro-hydraulic directional control 
valves 51 of hydromotors 50 are put on signal control lines 90, 91 
connected to control lever 34 for guiding wheel drive devices M.sub.v and 
M.sub.H when shift part 34, which is constructed as a shift lever, is 
moved out of neutral position o in direction v for forward travel and in 
direction z for reverse travel. An OR circuit 92 is connected to signal 
control lines 90, 91, which carry O signals when control lever 34 is in 
neutral. This OR circuit only emits an O signal as output signal at the 
neutral position of control lever 34, i.e., when wheel drive devices 
M.sub.V, M.sub.H are turned off. The inverted output signal of OR circuit 
92 is put on the one input of an AND circuit 93, the output of which is 
connected to the input line 78 of electronic switch 77, and the other 
input of which receives an L signal when one of direction-setting parts 35 
is actuated, so that an actuation of parts 35 is only effective if no 
wheel drive device M.sub.V, M.sub.H is turned on when O signals are on 
signal control lines 90, 91. As an additional safety measure in the 
circuit shown, make contacts 89' of a relay connected to electronic switch 
77 are cut into output lines 81, 82 of comparator 80 running to 
directional control valve 57 of adjusting motor SMb and back contact 102' 
of the same or of a separate relay 102 connected to electronic switch 77 
are cut into signal control lines 90 and 91, so that when electronic 
switch 77 is on, thus cutting in adjusting motor SMb, signal control lines 
90, 91 are interrupted, and thus any actuation of shift part 34 for 
guiding wheel drive devices M.sub.V, M.sub.H is ineffective, and after 
vertical axle 9b has been moved when electronic switch 77 is off, output 
lines 81, 82 of the comparator are interrupted and adjusting motor SMb is 
thus securely turned off, but a moving of shift part 34 for controlling 
the wheel drive devices via signal lines 90, 91 which are then closed can 
become effective. 
In the pivotable wheel pair electro-hydraulic directional control valve 51 
of wheel drive device M.sub.Vb is connected via AND circuits 94, 95 to 
signal control lines 90, 91, so that valve 51 is moved in correspondence 
with the moving of shift part 34 for controlling the wheel drive devices. 
For controlling the wheel drive device M.sub.Hb (FIG. 11) of the 
non-pivotable wheel pair 19b, control signal lines 90, 91 run over a 
change-speed mechanism 97 which is connected over lines 98 to 
direction-setting parts 35.sub.nl and 35.sub.nr for the 90.degree. 
position, that is, for pivoting the bogie truck in place, and which is 
constructed so that control signal lines 90', 91' from change-speed 
mechanism 97 are usually connected to signal control lines 90, 91 and 
carry the same control signals as they do after actuation of a 
direction-setting part 35.sub.nl, 35.sub.nr. However, outgoing signal 
control lines 90', 91' are separate from signal control lines 90, 91 and 
carry O signals, so that wheel drive device M.sub.Hb is turned off during 
pivoting in place and the non-pivotable wheel pair corotates freely. Or, 
outgoing signal control lines 90', 91' for the particular direction of 
pivoting selected are connected to signal control lines 90, 91 in such a 
manner that the non-pivotable wheel pair is driven in the proper direction 
of rotation. 
Furthermore, an actuation of shift part 34 for controlling wheel drive 
device M.sub.V, M.sub.H is only effective if all support legs 30 have been 
brought by lifting devices 32 into a completely retracted position in 
which the wheels rest securely on the ground. 
In wheel drive device M.sub.Mb the two inputs of AND circuits 94, 95 
connected to directional control valve 51 are connected together with 
lift-indicating signal transmitter 62 of the associated lifting device 
32.sub.V and only receive an L signal from it (contact 62b) if support leg 
30 is completely retracted, so that control signals supplied over signal 
control lines 90, 91 for moving directional control valve 51 are passed on 
from AND circuits 94, 95 to valve 51 only in this lifting state. In 
lifting device 32.sub.V the AND circuit 88 belonging to gate terminal 
61.sub.2 of directional control valve 61 is located on one input with the 
output signal of OR circuit 92. The other input of AND circuit 88 is 
connected to lift-indicating signal transmitter 62 of lifting device 
32.sub.V and only receives an O signal from it if support leg 30 is 
completely retracted. If the shift lever used as a shifting means 34 is 
moved out of its neutral position when support leg 30 is not completely 
retracted, an L signal from AND circuit 88 is put on gate terminal 
61.sub.2 of directional control valve 61, which places valve 61 from the 
neutral position into the work position, in which hydrocylinder 60 is 
connected to oil pressure and return lines 66 and 67 for moving the 
support leg up, and leg 30 is retracted. When the leg is retracted into 
the final position, lift-indicating signal transmitter 62 puts an O signal 
(inverted signal from contact 62b) on AND circuit 88 which causes 
directional control valve 61 to be placed back into the neutral position, 
whereby, however, support leg 30 remains in the completely retracted 
position. 
Wheel drive devices M.sub.H of the non-pivotable wheels can only be turned 
on by moving shift part 34 out of the neutral position o if support legs 
30 are completely retracted and if, in addition, the blocking by brake 
devices 21 has been cancelled. As is shown in FIG. 11 for wheel drive 
device M.sub.Hb, in the AND circuits 94' and 95' of directional control 
valve 51 the one inputs are connected to signal control lines 90', 91' and 
the other inputs are connected together to the output of AND circuit 106, 
the one output of which is connected to lift-indicating device 62 of 
lifting device 32 for the associated support leg 30 and only receives an L 
signal from lift-indicating signal transmitter 62 is support leg 30 is 
completely retracted, and the other input of which is connected to 
blocking indicating signal transmitter 26 of brake device 21 and only 
receives an L signal from signal transmitter 26 if the blocking has been 
properly released (contact 26b). If support leg 30 is not completely 
retracted and/or if the blocking has not been properly released, an O 
output signal of AND circuit 106 blocks the two AND circuits 94' and 95' 
and control signals on signal control lines 90', 91' are ineffective. 
The one control input 25.sub.1 of electro-hydraulic valve 25 for 
single-acting hydrocylinder 24, which is used as power producer 22 for 
releasing the blocking counter to the action of spring 23, receives the 
output signal of AND circuit 104 as a control signal, the one input of 
which is connected over line 96 to the output of OR circuit 92, which 
detects the signals of signal control lines 90, 91 (FIG. 10). The other 
input of AND circuit 104 is connected to blocking indicating signal 
transmitter 26 and carries an O signal only when the blocking has been 
properly released. In the other AND circuit 105 belonging to the other 
control input 25.sub.2 of directional control valve 25 the one input is 
connected over inverter 107 to line 96, and the other input, connected to 
blocking indicating signal transmitter 26, carries an O signal only when 
the blocking is complete. When shift part 34 for controlling the wheel 
drive devices is moved out of its neutral position, AND circuit 105 
blocks, and AND circuit 104 receives an L signal on its one input, so that 
it puts a positioning signal on gate terminal 25.sub.1 if the brakes block 
or are not properly released (inverted signal from contact 26b), and 
hydrocylinder 24 is connected to pressure oil line 66. Then, if the 
blocking is properly released, AND circuit blocks and directional control 
valve 25 is set back into its neutral position, whereby, however, the 
brakes stay released. If shift part 34 is then set back into its neutral 
position, AND circuit puts a positioning signal on control input 25.sub.2, 
by means of which hydrocylinder 24 is connected over directional control 
valve 25 to oil return line 67, so that spring 23 brings the brake device 
into blocking position, and when a proper blocking has been achieved, AND 
circuit blocks and directional control valve 25 returns to its neutral 
position. 
In lift device 32.sub.H control input 61.sub.2, over which directional 
control valve 61 is placed into work position for retracting support leg 
30 by hydrocylinder 60, receives positioning signals from AND circuit 88', 
in which, as in AND circuit 88 if lift device 32.sub.V, the one input is 
connected to the output of OR circuit 92 and the other input is connected 
to lift indicating signal transmitter 62 (contact 62b). An AND circuit 87' 
can be present for the other control input 61.sub.1, even though the 
extending of rear support leg 30 should occur automatically, as, for 
example, during the moving of vertical axle 96. The inputs of AND circuit 
87' are then connected just as the inputs of AND circuit 87 in lift device 
32.sub.V. 
As was already mentioned, directional control valves 61 of lift devices 
32.sub.V, 32.sub.H are associated with hand-actuated lift-switch parts 63, 
64 with positioning signals which can be supplied to control inputs 
61.sub.1 and 61.sub.2 for extending and retracting the support legs as 
desired. In the front lift device 32.sub.V the lift-switch parts 63, 64 
are only active when switch part 36 for lift release on control panel 33 
is actuated and adjusting motor SM.sub.b as well as wheel drive device 
M.sub.Vb (FIG. 10) are turned off. A NOR circuit 101, the one input of 
which is connected to electronic switch 77 and the other input of which is 
connected to the output of OR circuit 92, only puts an L signal on the 
input of an AND circuit 100 if electronic switch 77 is cut out, i.e., no 
direction-setting part 35 is actuated, and signal control lines 90,91 are 
carrying O signals with shift part 34 set at its neutral position and 
adjusting motor SM.sub.b and wheel drive device M.sub.Vb are therewith 
turned off. The other input of AND circuit 100 is connected to switch part 
36 for lift release and receives an L signal when it is actuated. The 
output of AND circuit 100 is connected over lift-switch parts 63 and 64 to 
control inputs 61.sub.1 and 61.sub.2 of directional control valve 61, and 
an L signal on the output of AND circuit 100 can be put on control input 
61.sub.1 or 62.sub.2 by actuating one or the other lift-switch part 63 or 
64. In the rear lift device 32.sub.H (FIG. 11) each lift-switch part 63, 
64 is connected to the output of an AND circuit 103 with three inputs, the 
one input of which is connected over line 99 to switch part 36 for the 
lift release, the second input of which is connected to the output of 
inverter 107 connected to OR circuit 92, and the third output of which is 
connected to blocking indicating signal transmitter 26 for receiving an L 
signal when the wheels are blocked (contact 26a), so that an actuation of 
lift-switch parts 63, 64 is only effective if switch part 36 is actuated, 
wheel drive device M.sub.Hb is turned off and brake device 21 is in 
blocking position. Since brake device 21 is automatically brought into 
blocking position when wheel drive device M.sub.Hb is turned off, AND 
circuit 103 actually needs only two inputs; however, the third input 
connected to blocking indicating signal transmitter 26 constitutes an 
additional check for the proper functioning of the control device. 
As is customary in control devices, signal devices which are preferably 
optical are associated with at least a part of the switch parts to 
indicate their switch state. Thus, optical signal devices 39 for the 
individual direction-setting parts 35 are provided on control panel 33, 
for example, which indicate the particular actual position of the 
pivotable wheel axle in one color, e.g. green, and the new position 
selected in another color, e.g. red, until the pivotable wheel axle has 
reached the new position. 
In order to show that when main switch 37 (FIG. 10) is cut in, an actuation 
of switch parts is only effective if safety switch 38 is actuated at the 
same time, these two switches 37, 38 are shown connected in series to the 
plus pole of a battery B which supplies the operating voltage for the 
control device, so that operating voltage is available for the individual 
control circuits of the control device only when switches 37, 38 are cut 
in. In practice, more suitable circuits are selected for this purpose, 
which are simple in construction and require no further explanation. 
Commercially available logical modules can be used to control the 
individual directional control valves, so that the entire control device 
can be composed essentially of such modules. Other, especially electrical 
devices, can of course be used instead of the hydraulic devices. Thus, 
especially the relatively low-performance hydraulic devices like, for 
example, the pivot motors, the stop devices and the power producers can be 
replaced by corresponding electrical devices. 
Although one embodiment of the invention has been now disclosed in detail, 
it should be appreciated that various changes thereto can be made and 
still fall within the scope of the appended claims.