Reversible caster device having brake mechanism

A caster device wherein a wheel frame mounted on a mounting base mounted on the lower surface of a traveling body in such a manner that the wheel frame may be rotated horizontally with respect to the mounting base comprises a swivel frame and a pivotal frame which can rotate together with the swivel frame and can pivotally move in a lateral direction within a preselected range, the pivotal frame having a wheel mounted thereon, the caster device comprising a direction restraining device capable of engaging the mounting base and pivotal frame in one direction of traveling of the wheel, and a brake device for applying a braking action to the wheel when it is changed over in traveling direction, whereby the pivotal frame is pivotally moved by the braking action resulting from the changeover of the traveling direction of the wheel to automatically bring the wheel frame into a freely swiveling state or a restrained state depending on the traveling direction.

FIELD OF THE INVENTION 
The present invention relates to a caster device which can assume two 
states, namely a free state wherein a leg rotatably supporting thereon a 
caster can be freely swiveled with respect to a base and a restrained 
state wherein the swiveling of the leg is restrained, and particularly to 
a caster device in which the changeover between the free state and the 
restrained state can be effected by changing the moving direction of the 
wheel. 
BACKGROUND OF THE INVENTION 
It is known to provide a traveling body such as a large suitcase, a luggage 
carrier, various wagons, and the like with four caster wheels mounted on 
the lower surface thereof so as to be positioned at the four corners 
thereof. If these four wheels are all designed to be swiveled freely, the 
traveling direction will not be fixed, whereas if all the wheels are 
restrained from swiveling, it will difficult to move the body in a curved 
fashion. It is therefore desirable for the two wheels that are forward 
relative to the traveling direction to be free to swivel and the two 
wheels that are rearward to be restrained from swiveling. However, it has 
been impossible for conventional caster devices to provide the wheel 
states as mentioned above, regardless of the traveling direction, merely 
by changing the traveling direction of the traveling body without 
performing any operation. 
The present inventor has proposed a caster device which can meet the 
requirements as described hereinbefore. Namely, his Laid-open Japanese 
Patent Application No. 55-156702 discloses a caster device in which the 
swivel shaft of the wheel is provided integrally with a supporting frame 
of the wheel, the swivel shaft being rotatably supported on a base 
housing, an engaging element and a locking member having a locking portion 
which engages the engaging element to restrain the rotation of the swivel 
shaft are provided on the side of the swivel shaft and the side of the 
base housing, respectively, and the engaging element and the locking 
portion of the locking member are engaged or disengaged responsive to the 
urging of the engaging element resulting from the swiveling force of the 
supporting frame so that the changeover between the free state and 
restrained state of the wheel may be effected by changing the moving 
direction of the wheel. According to this caster device, it is always 
possible to freely swivel the two front wheels and to restrain the 
swiveling of the two rear wheels, irrespective of the traveling direction 
of the traveling body. However, in the case the traveling body has a great 
weight or in the case the traveling body is loaded with heavy articles, 
the aforesaid engaging element is apt to become disengaged from the 
locking portion of the locking member due to the traveling inertia 
resulting from said weight, thus giving rise to the situation that the 
swiveling of the rear wheels may not be restrained. 
SUMMARY OF THE INVENTION 
It is therefore an object of the present invention to provide a caster 
device which can positively perform the switchover of the states of a 
wheel leg from a swivel free state to a swivel restraining state, or vice 
versa, in response to the changeover of the moving direction of the wheel. 
The caster device in accordance with the present invention has been 
achieved on the basis of a conception totally different from that of the 
caster device proposed as mentioned hereinbefore. The caster device of the 
present invention is characterized in that wheels are supported on a 
pivotal frame separately from a swivel frame which can be swiveled about a 
main shaft of a mounting base; the pivotal frame is pivotally mounted on 
the swivel frame pivotably by a preselected angle through a pivotal shaft 
which is horizontal and positioned laterally away from the main shaft; the 
mounting base and pivotal frame are provided with a direction restraining 
means which is engageable in either traveling direction of the wheel; and 
a brake means is provided to apply braking action to the wheels when the 
traveling direction of the wheels is changed over, and said direction 
restraining means is engaged or disengaged by the pivotal movement of the 
pivotal frame resulting from the braking action and by the swiveling force 
of the swivel frame resulting from the changeover of the traveling 
direction.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS 
With particular reference to FIGS. 1 and 2, a mounting base 10 mounted on 
the lower surface of a traveling body 1 has a vertical main shaft 11 
substantially in a central portion thereof, and a connecting portion 22 of 
a swivel frame 20 having a leg 21 on either side thereof is horizontally 
and rotatably supported on the main shaft 11. Reference numeral 12 
designates an external rolling ball retained between an annular groove 13 
of the base 10 and an annular groove 23 of the swivel frame 20, whereas 
reference numeral 14 designates an internal rolling ball retained between 
a ball receiving plate 15 caulked to the lower end of the main shaft 11 
and the connecting portion 22 of the swivel frame 20. Both the balls are 
provided to render as smooth swiveling of the swivel frame 20 relative to 
the base 10 as possible. 
An axle 6 of a wheel 4 is supported by means of a pivotal frame 30 
separately provided internally of the swivel frame 20, unlike the 
arrangement of the conventional caster devices. The pivotal frame 30 is in 
the form of a downwardly directed U-shape having a leg 33 on either side 
and a connecting portion 34 and is pivotally mounted on the swivel frame 
20 through a pivotal shaft 35 positioned laterally away from the main 
shaft 11 with the upper portions of the legs 33 being horizontal, the 
pivotal frame 30 having the axle 6 of the wheel 4 supported downwardly 
thereof. Thus, the pivotal frame 30 and the wheel 4 may be pivotally moved 
about the pivotal shaft 35 within a range determined by a slot 24 which is 
provided in the leg 21 of the swivel frame 20 and into which the axle 6 is 
inserted. In this manner, in the present invention, the wheel frame is 
composed of the swivel frame and the pivotal frame which can rotate with 
respect to the swivel frame but can be pivotally moved laterally within a 
given range. 
The base 10 and the pivotal frame 30 are provided with a direction 
restraining means 40 which is engaged and disengaged responsive to said 
pivotal movement of the pivotal frame 30. This direction restraining means 
40 is provided with an engaging pin 42 biased downwardly by means of a 
compression spring 41 like a coiled spring accommodated within a hollow 
frame 38 provided on the lower surface of the base 10, and the pivotal 
frame 30 has an L-shaped bent portion 36 upwardly of the connecting 
portion thereof, which bent portion is formed with a cut groove 43 for 
receiving the engaging pin 42 therein, and the upper surface of the bent 
portion 36 of a portion on both sides of the cut groove 43 is formed into 
a guide surface 44. As best seen in FIG. 2, when the pivotal frame 30 is 
positioned at one end of pivotal movement, the cut groove 43 may come into 
engagement with the engaging pin 42 but when the pivotal frame 30 reaches 
the other end of pivotal movement, the cut groove 43 is released from 
engagement with said pin. When the pivotal frame 30 is positioned at such 
end of pivotal movement that the cut groove 43 is brought into engagement 
with the engaging pin 42, if the swivel frame 20 is swiveled, the engaging 
pin 42 is raised by the guide surface 44 of the pivotal frame 30 against 
the compression spring 41 and the pin 42 is finally moved into the cut 
groove 43. 
The pivotal frame 30 is urged, by means of a tension spring 45 (FIG. 3) 
retained between the pivotal frame 30 and the swivel frame 20, towards the 
end of pivotal movement at which the cut groove 43 is engaged with the 
engaging pin 42, but a brake pawl 46 wound and disposed on the pivotal 
shaft 35 is provided to apply a force to the pivotal frame 30 towards the 
other end of pivotal movement against the force of the tension spring 45 
or the force by which the axle 6 tends to be positioned rearwardly 
responsive to the traveling of the wheel 4. This brake pawl 46 is in 
contact with the outer circumference of the wheel 4 and will not impede 
rotation of the wheel 4 under the traveling condition wherein the axle 6 
of the wheel 4 is positioned rearwardly of the main shaft 11 but when the 
traveling direction is changed over into a direction opposite the 
aforesaid traveling condition, the braking action is applied to the wheel. 
Reference numeral 47 designates a loop mounted on a tongue portion 48 of 
the brake pawl 46 with respect to the pivotal shaft 35, and when the loop 
47 is extended over a hook 49 provided on the upper end of the swivel 
frame 20, the brake pawl 46 is disengaged from the wheel 4. 
Caster devices constructed as described hereinbefore are respectively 
mounted at the four corners on the bottom surface of the traveling body 1 
by the base 10 as shown in FIG. 4 but should be mounted so that the 
direction restraining means 40 of the respective caster devices are 
positioned at the upward end. When the traveling body 1 is urged to be 
moved in the direction as indicated by the arrow A under such a condition, 
the brake pawl 46 in every caster device is in a state wherein it bears on 
the wheel 4 but the brake pawl 46 is inclined in a rotational direction of 
the wheel 4, for which reason the pawl will not impede rotation of the 
wheel 4. At this time, the engaging pin 42 of the direction restraining 
means 40 of the first caster device 2 positioned frontwardly of the moving 
direction is not fitted into the cut groove 43, and therefore, the swivel 
frame 20 is in a state wherein it is rotatable with respect to the base 
10, that is, the wheel is placed in a freely swiveling condition. The 
engaging pin 42 of the direction restraining means 40 of the second caster 
device 3 positioned rearwardly of the moving direction is fitted into the 
cut groove 43 and therefore the swivel frame 20 assumes a state wherein it 
is restrained with respect to the base 10, that is, the wheel is 
restrained from swiveling and the traveling body 1 can be easily changed 
over in direction to provide stabilized travel. 
When the traveling direction of the traveling body 1 is reversed from the 
aforesaid condition, the brake pawls 46 of the first and second caster 
devices respectively exert braking action on the wheels 4, as a 
consequence of which the axle 6 is moved rearwardly with respect to the 
traveling direction within the slot 24 of the swivel frame 20. Namely, the 
wheel 4 has been so far positioned rearwardly of the previous traveling 
direction by the force applied to the axle responsive to the traveling of 
the wheel and by the force of the tension spring 45 but the rotation of 
the wheel is stopped by the aforementioned braking action. However, since 
the traveling body 1 travels in the direction as indicated by the arrow B, 
the pivotal movement of the pivotal frame 30 about the pivotal shaft 35 
causes movement of the axle 6 in the direction as indicated by the arrow 
in FIG. 5. As a result, the L-shaped bent portion 36 is moved downwardly 
and in the second caster device 3, the cut groove 43 positioned in the 
upper end of the L-shaped bent portion 36 is released from engagement with 
the engaging pin 42 with the result that the wheel so far restrained in 
traveling direction becomes free to swivel. 
When the traveling body is further urged to move in the direction as 
indicated by the arrow B, the swiveling force about the main shaft 11 is 
applied to the swivel frame 20 since the axle 6 is positioned frontwardly 
of the main shaft 11. As a result, the swivel frame 20 swivels along with 
the pivotal frame 30 and the wheel 4 in such a manner that the axle 6 is 
positioned rearwardly of the main shaft 11, and with this swiveling, the 
axle 6 is again moved within the slot 24 as shown in FIG. 6 to raise the 
cut groove 43 of the pivotal frame 30 up to a position at which it comes 
into engagement with the engaging pin 42. Therefore, in the first caster 
device 2, the engaging pin 42 is fitted into the cut groove 43 to restrain 
the traveling direction whereas the other second caster device 3 becomes 
free to swivel. Accordingly, the condition assumed is that the leg 33 of 
the caster device 2 positioned frontwardly swivels freely whereas the leg 
33 of the caster device 2 positioned rearwardly becomes restrained in 
swivel, whereby the traveling body 1 can be easily changed over in 
direction to provide stabilized traveling. 
As described hereinbefore, the caster device in accordance with the present 
invention provides automatic switchover in which swiveling of the rear 
wheels is restrained whereas swiveling of the front wheels is made free in 
response to the operation in which the traveling direction is changed over 
to the direction A or to the direction B. 
As is apparent from the foregoing, it will be noted that switchover is 
effected in the case the front and rear bases 10 are mounted on the lower 
surface of the traveling body in such a manner that the engaging pin 42 
side is on the rear side or front side of the traveling direction. If the 
front and rear bases 10 should be mounted in one and the same direction, 
both the front and rear wheels are restrained in swivel in one traveling 
direction whereas both the wheels assume a freely swiveling state in the 
other traveling direction. 
Next, FIG. 7(A) shows an example of the case in which both front and rear 
wheels are restrained in swivel, and the front and rear wheels are 
required to be restrained for example, in the case wherein as shown in 
FIG. 7(B), on an inclined floor, the traveling body 1 is urged to travel 
in a direction perpendicularly to the inclination of the floor surface or 
in the case wherein the traveling body 1 is stopped on the inclined floor 
surface. Now, when in the condition of FIG. 6, the loop 47 of the tongue 
portion 48 on the first caster device 2 is extended over the hook 49, the 
brake pawl 46 is disengaged from the wheel 4 as shown in FIG. 7(A). When 
the traveling direction is changed over to the direction A under said 
condition, the second caster device 3 is swiveled by the aforementioned 
operation to assume a state in which the leg 33 is restrained in swivel. 
At this time, the brake pawl 46 is disengaged from the wheel 4 on the side 
of the first caster device 2 and therefore no swiveling of the swivel 
frame 20 occurs. Thus, when the loop 47 on the side of the second caster 
device 3 is likewise extended over the hook 49, the brake pawl 46 is 
disengaged from the wheel 4 as shown in FIG. 7(A), and therefore, it 
assumes a state wherein neither the front nor the rear caster devices are 
subjected to the braking action caused by the brake pawl 46, that is, both 
the front and rear caster devices are restrained in swivel regardless of 
whether the traveling direction is changed over to direction A or B. 
For the reason as described hereinbefore, since the traveling body 1 having 
four caster devices mounted on the lower surface thereof travels only in 
the linear direction, it can travel linearly in a direction crosswise of 
the inclined surface, and even if the traveling body is stopped halfway of 
the inclined surface, it will not move towards the inclined direction. It 
will suffice to provide the caster devices restrained in swivel, one for 
the front side of the traveling body and one for the rear side thereof, 
and therefore, the other caster devices need not be provided with the loop 
47 and hook 49. 
It should be appreciated that if the loop 47 is removed from the hook 49 to 
bring the brake pawl into contact with the wheel, the mode can be changed 
over so that the front side is swiveled freely whereas the rear side is 
restrained in swivel similarly to the previous embodiment. 
FIGS. 8 through 11 show another embodiment of the brake member for applying 
the unidirectional braking action to the wheel 4, in which the same 
components as those of FIGS. 1 through 3 are denoted by like reference 
numerals. In this embodiment, a brake member comprises a brake screw 50 in 
the form of a counter-sunk screw, which brake screw 50 is supported in a 
slot 52 of a plate-like screw supporting tongue 51 having one end wound 
about the pivotal shaft 35. The screw supporting tongue 51 extends towards 
the side opposite the side of the cut groove 43 of the pivotal frame 30 
with respect to the pivotal shaft 35, and the slot 52 is directed in the 
circumferential direction of the wheel 4. The brake screw 50 is inserted 
from the bottom into the slot 52 so that a counter-sunk portion 50a 
thereof may bear on the outer peripheral portion of the wheel 4, and a 
stop ring 53 is snap-fitted about the insertion end. On one side at the 
lower end of the slot 52 is provided an inclination forcing plate 54 for 
inclining the brake screw 50 with respect to a center line L (see FIG. 9) 
of the wheel 4 through an angle of .alpha., and the brake screw 50 is 
urged to be biased towards the wheel 4 side by means of a tension spring 
55 stretched between the screw supporting tongue 51 and the swivel frame 
20. 
In the caster device constructed as described hereinbefore, in the 
traveling direction as indicated by the arrow A at which the main shaft 11 
is positioned frontwardly of the wheel 4, as shown in FIG. 8, the brake 
screw 50 is positioned at the lower end of the slot 52 by the frictional 
force from the wheel 4, at which time said screw is inclined through the 
angle of .alpha. from the center line L of the wheel 4 by the inclination 
forcing plate 54 as mentioned hereinbefore, and therefore it is rotated in 
a direction as indicated by the arrow in FIG. 9 by the frictional force 
resulting from the rotation of the wheel 4. That is, the rotation of the 
wheel 4 is not impeded by the brake screw 50. 
Conversely, when the traveling direction is reversed to the direction of 
arrow B as shown in FIG. 11, the brake screw 50 is moved up within the 
slot 52 by the frictional force from the wheel 4. When the brake screw 
reaches its upper limit, the screw is inclined, and the edge of the 
countersunk portion 50a is forced into the wheel 4 under the influence of 
the tension spring 55. For this reason, braking is applied to the wheel 4, 
as a consequence of which the pivotal frame 30 is pivotally moved to 
further swivel the swivel frame 20. Accordingly, the traveling direction 
may be changed over to restrain the swiveling of the wheel or render it 
free, in a manner similar to that of the previous embodiment. 
FIGS. 12 through 16 show an embodiment similar to the caster device shown 
in FIGS. 8 through 11 but wherein the brake screw 50 may be released from 
the wheel 4 by means of a brake releasing lever 60. As best seen in FIG. 
15, the brake releasing lever 60 comprises a bent round rod having a 
locking portion 60a and an operating portion 60b positioned at opposite 
sides of the swivel frame 20, an engaging portion 60c positioned within 
the swivel frame 20 and opposed rotational shaft portions 60d fitted in 
the leg 21 of the swivel frame 20, the engaging portion 60c being 
positioned at the lower surface of the engaging tongue 51a provided at the 
lower end of the supporting tongue 51 of the brake screw 50. In mounting 
the brake releasing lever 60 on the swivel frame 20, the operating portion 
60b is inserted into a hole 61 in one leg 21 to position one rotational 
shaft portion 60d within the hole 61 and the locking portion 60a is 
inserted into a hole 63 of an auxiliary plate 62 to position the other 
rotational shaft portion 60d within the hole 63, under which condition the 
rotational shaft portion 60d on the locking portion 60a side is inserted 
into a recess 64 of the other leg 21 of the swivel frame 20 and the 
auxiliary plate 62 is secured to the swivel frame 20 by means of a set 
screw 65 and a locking pin 66. 
The brake releasing lever 60 is urged by a compression spring 67 inserted 
between the operating portion 60b and the leg 21 of the swivel frame 20, 
in the direction in which the locking portion 60a bears on the auxiliary 
plate 62, and on the other hand, when the locking portion 60a is 
positioned above or below the locking pin 66 against the aforesaid urging 
force, the locking pin 66 causes the brake screw 50 to be out of contact 
or in contact with the wheel 4. 
That is, when the operating portion 60b of the brake releasing lever 60 is 
tilted downwardly as shown by the solid lines in FIG. 16, the locking 
portion 60a assumes a position below the locking pin 66 beyond the latter 
so that the supporting tongue 51 is raised through the engaging portion 
60c and the engaging tongue 51a with the result that the brake screw 50 is 
released from the wheel 4. Thus, the braking action caused by the brake 
screw 50 is not effected and therefore the swiveling of the front and rear 
wheels may be restrained as shown in FIG. 7(A). On the other hand, when 
the operating portion 60b of the brake releasing lever 60 is positioned 
substantially horizontally as shown by the dotted lines in FIG. 16, the 
engagement between the engaging portion 60c and the engaging tongue 51a is 
released so that the brake screw 50 bears on the wheel 4, whereby the 
switchover between the restraining of swivel and free swivel of the wheels 
on the basis of the braking action can be carried out in a manner similar 
to that as previously described. In accordance with this embodiment, there 
is provided an advantage in that the brake member may be brought into 
engagement with or disengagement from the wheel in a simple manner by the 
operation of bringing the brake releasing lever 60 up or down. 
FIGS. 17 through 21 show a further embodiment of brake means which applies 
braking action with respect to the unidirectional rotation of the wheel 4. 
In this embodiment, the brake means comprises an arrangement wherein breke 
blades 57 are extended on opposite ends of a cylindrical rotational member 
56 loosely fitted in the pivotal shaft 35, said brake blade 57 having its 
forward end edge 58 placed adjacent the outer peripheral surface of a rim 
5 protruded from each side of the wheel 4. 
When the aforementioned caster device travels forward in a direction as 
indicated by the arrow A in FIG. 17, the wheel 4 is not subjected to the 
braking action under the condition wherein the forward end edge 58 of the 
brake blade 57 is in contact with the outer edge of the rim 5. Since the 
cut groove 43 of the bent portion 36 is fitted in the engaging pin 42, the 
wheel 4 is restrained in swivel and can only travel straight. 
However, when the moving direction of the caster device is reversely 
changed over as indicated by the arrow B in FIG. 19, the forward end edge 
58 of the brake blade 57 is forced into the outer edge of the rim 5 to 
thereby exert the braking force on the wheel 4, and said braking force and 
the movement of the caster device cause the pivotal movement of the 
pivotal frame 30 about the pivotal shaft 35 until the axle 6 reaches the 
other end of the slot 24. When the pivotal frame 30 is pivotally moved as 
mentioned above, the cut groove 43 is disengaged from the engaging pin 42, 
whereby the swivel frame 20 and pivotal frame 30 may be swiveled freely 
about the main shaft 11, and the movement of the caster device causes the 
swiveling of both frames 20, 30 and wheel 4 about the main shaft 11 
through 180 degrees (see FIG. 20). 
Under this condition, since nothing engages the cut groove 43, the wheel is 
in a freely swiveling state and may be moved in a straight and or curved 
manner. On the other hand, when the moving direction of the caster device 
is changed over while maintaining the aforesaid condition, the braking 
force is applied to the wheel 4 by the brake blade 57 and both frames 20, 
30 and wheel 4 swivel while the pivotal frame 30 is pivotally moved. When 
both the frames and the wheel are swiveled through 180 degrees, the bent 
portion 36 causes the engaging pin 42 to be forced up from the bottom so 
that the cut groove 43 comes into engagement therewith to have the wheel 
restrained in swivel as shown in FIG. 17 to allow it to travel straight 
alone. 
FIGS. 22 and 23 show a still another embodiment of the caster device in 
accordance with the present invention, in which the pivotal frame 30 is 
provided externally of the swivel frame 20. That is, the pivotal shaft 35 
mounted upwardly between the legs 21 of the swivel frame 20 has its ends 
projected from the outer surface of the legs 21, and an upper portion of 
leg 33 of the pivotal frame 30 is jounalled on said projected portion. The 
connection portion 34 is positioned between the external upper ends of the 
legs 33, and the bent portion 36 formed with the cut groove 43 is aligned 
with the upper edge of the connection portion 34. 
Also, in the embodiment of the caster device shown in FIGS. 22 and 23, when 
the moving direction is reversed, the forward end edge 58 of the brake 
blade 57 presses the rim 5 of the wheel 4 to thereby exert braking force 
on the wheel 4, and the braking force and the moving action of the caster 
device cause the pivotal movement of the pivotal frame 30 about the 
pivotal shaft 35. Thus, whenever the moving direction is changed, the 
caster device is changed in mode from the swivel restraining condition to 
the free swivel condition or from the free swivel condition to the swivel 
restraining condition. 
Further, in either embodiment shown in FIGS. 17 and 22, a brake mechanism 
has a tongue 48 extended from the rotational member 56, the tongue 48 
having a loop 47 provided at the free end thereof, and when the loop 47 is 
engaged with the hook 49 provided upwardly of the swivel frame 20, the 
brake blade 57 is disengaged from the side rim 5. 
Thus, even if the moving direction of the caster device is changed over, 
the braking force is not exerted on the wheel since the brake blade 57 is 
not in contact with the rim 5. This is particularly effective in the case 
wherein if the wheel is restrained in swivel, even if the moving direction 
of the caster device is changed over, the device is advanced straight 
alone while maintaining such a restraining condition. 
It should be appreciated that the forward end edge 58 of the brake blade 57 
may be formed with teeth so that the forward end edge may be readily 
forced into the outer peripheral portion of the rim 5, and the brake 
mechanism can be mounted on a portion other than the support shaft. 
Next, a description will be made in connection with FIGS. 24 and 25 of a 
mechanism in which the wheel 4 of the caster device is placed in a freely 
movable state, that is, the wheel can be directed in any direction. The 
caster devices having the construction so far described may be employed. 
The caster device is accommodated within a hollow frame 38 provided on the 
lower surface of the base 10, a flange-like receptacle 42' is provided 
halfway in height of the engaging pin 42 normally downwardly projected by 
the urging element 41, and an operating member 16 is provided adjacent the 
receptacle 42'. The operating member 16 comprises an operating element 16a 
provided at the outer forward end of a plate member 16b extended frm the 
interior of the hollow frame 38 towards the exterior thereof, and a forked 
operating element 16c holding the engaging pin 42 therebetween at the 
other end, the plate member 16b being biased towards the bottom of the 
hollow frame 38 by means of a laterally directed U-shaped plate spring 39 
provided internally of the hollow frame 38. The forward end of the forked 
operating element 16c is pointed, which is placed adjacent the lower 
surface of the receptacle 42' of the engaging pin 42. Thus, if the 
operating element 16a of the operating member 16 is extended from the 
hollow frame 38, the forward end of the operating element 16c is not borne 
on the receptacle 42', and therefore the engaging pin 42 is projected from 
the lower surface of the hollow frame 38 by the urging element 41, whereby 
the pin is engaged with or disengaged from the cut groove 43 in the bent 
portion 36 provided on the connection portion 34 of the pivotal frame 30. 
When the cut groove 43 engages the engaging pin 42, the swivel frame 20 
and the pivotal frame 30 cannot be horizontally rotated about the main 
shaft 11 and therefore the wheel 4 travels straight. However, when the 
operating element 16a is forced towards the hollow frame 38 to move the 
plate member 16b, the forked operating element 16c is driven into the 
lower surface of the receptacle 42', and therefore the engaging pin 42 is 
moved up through the thickness of the operating element 16c and hidden 
into the hollow frame 38 (FIG. 25). As a result, the engagement of the cut 
groove 43 of the bent portion 36 with the engaging pin is released so that 
the swivel frame 20 and pivotal frame 30 may be freely rotated 
horizontally about the main shaft 11, thus placing the wheel 4 in a free 
traveling state in which the wheel may be directed in any direction. 
Accordingly, in the caster device with the operating element 16 forced in, 
when the traveling direction thereof is changed, the braking is exerted on 
the wheel so that the pivotal frame 30 supporting the wheel 4 thereon is 
always rotated about the main shaft 11. 
Next, a description will be made of a further embodiment of a mechanism, in 
connection with FIGS. 26 to 30, in which the pivotal movement of the 
pivotal frame 30 is stopped to maintain the engagement between the 
engaging pin 42 and the cut groove 43 to thereby restrain the swiveling of 
the wheels. 
A wheel swivel restraining mechanism 71 in accordance with this embodiment 
has an arrangement wherein a flat shaft 72 extended through a position not 
impairing the pivotal movement of the pivotal frame 30 upwardly of the 
swivel frame 20 is integrally provided with a control member 73, the shaft 
72 being rotated so that the pivotal frame 30 may be stopped or released 
by the control member 73. The control member 73 has a pair of pressing 
elements 74 which extend obliquely and downwardly, each of the pressing 
members 74 having an outwardly bent control element 75 provided on the 
upper end thereof. On one end of said shaft 72 is provided a bent first 
operating portion 76 positioned externally of the side of the swivel frame 
20, and on the other end of the shaft 72 is provided a stopper portion 77 
positioned externally of the other side. The stopper portion 77 comprises 
a stopper element 78 which bears on the side edge of said side, a pawl 
element 79 which presses against said side and a second operating portion 
80 which extends downwardly, the stopper portion being rotated integral 
with the shaft 72. 
When the aforesaid control mechanism 71 is mounted on the swivel frame 20, 
each of pressing elements 74 of the control member 73 is positioned 
between the brake blade 57 of the control mechanism and the side 33 of the 
pivotal frame 30 and placed adjacent the receptacle 59. When the shaft 72 
is rotated, each of control elements 75 of the control member 73 is placed 
adjacent a stepped engaging portion 32 formed halfway of the side edge of 
each side 33 of the pivotal frame 30. The shaft 72 urges the pawl element 
79 of the stopper portion 77 so that the pawl element 79 may come into 
pressure contact with the external surface of the side 21 by means of a 
coiled spring 81 wound about the shaft 72. 
In the structure as described hereinbefore, when the shaft 72 is rotated by 
the first operating portion 76 or the second operating portion 80 to turn 
the control member 73 upwardly, each pressing element 74 causes the 
receptacle 59 of the brake blade 57 to be forced up, as a consequence of 
which the end edge 58 of the brake blade 57 is released from the side 5 of 
the wheel 4. At the same time, each control element 75 comes into 
engagement with the stepped engaging portion 32 formed in each side 33 of 
the pivotal frame 30 whereby the pivotal frame 30 is not pivotally moved. 
In this manner, when each caster device of carriers is driven by the 
control member 73, braking is not applied to the wheel and the pivotal 
frame 30 becomes fixed to the swivel frame 20. Accordingly, when the 
control member 73 is actuated under the condition that the cut groove 43 
of the pivotal frame 30 is fitted in the engaging pin 42, the wheels in 
all caster devices become fixed, and even if the carrier is moved 
crosswise to an inclined surface, no rolling occurs, and the carrier can 
remain stationary in a direction perpendicular to the inclined surface. It 
will be noted that the stopper element 78 of the stopper portion 77 
provided on the control mechanism 71 impinges upon the side edge of the 
side 21 of the swivel frame 20 to control the range of rotation of the 
control member 73 and is resiliently fitted by means of a coiled spring 81 
into either of two depressions (not shown) formed in the outer surface of 
the side 21 to locate the control member into one case in which the 
control member acts and the other case in which the control member does 
not act (FIG. 30). Also, the operating member 16 shown in FIGS. 24 and 25 
and the aforementioned wheel restraining mechanism 71 may be used so that 
the front wheels in the traveling direction of the carrier may be placed 
in a locked condition whereas the rear wheels thereof are placed in a 
freely traveling condition. That is, the mechanism 71 of the front caster 
device is actuated to stop the pivotal movement of the pivotal frame and 
the operating member 16 of the rear caster device is forced in to 
introduce the engaging pin 42 into the hollow frame 38. In this manner, 
the front wheels become locked whereas the rear wheels become freed. Thus, 
a heavily loaded carrier can be easily pushed upwardly along an inclined 
surface. 
Briefly, it will be apparent from the foregoing that in accordance with the 
present invention, a caster device comprises a swivel frame and a pivotal 
frame pivotally moved by a brake mechanism, the pivotal frame being 
engaged or released by a stopper mechanism to thereby place the caster 
frame in a locked or freely traveling condition, and a control mechanism 
is provided to lock or pivotally move the pivotal frame. If these various 
mechanisms are suitably operated to mount the caster devices on the 
carrier, the front caster devices may be always brought into a freely 
traveling condition whereas the rear caster devices all in a locked 
condition or vice versa, and in addition, the all caster devices can be 
brought into a freely traveling condition or a locked condition. As 
described above, since the present device may be used in a variety of 
modes, it is materially effective for use with carriers. Moreover, the 
above-described various mechanisms merely need be rotated or slidably 
moved and so they can be operated in a simple manner, and therefore, they 
may be applied not only to handcarts but to apparatuses which use caster 
devices for wagon vehicles, moving beds, and the like, in dining rooms, 
restaurants, hospitals, etc. 
Obviously, many modifications and variations of the present invention are 
possible in light of the above teachings. It is therefore to be understood 
that within the scope of the appended claims, the present invention may be 
practiced otherwise than as specifically described herein.