Convertible leg/roller structure

Convertible leg/roller structure for supporting an easel or other object in either a stationary position or a movable position. The leg can be moved to position either a stationary pad or a roller in contact with the ground or other supporting surface. A latch is provided for locking the leg in one of these two positions.

This invention pertains generally to support structures for easels and the 
like, and more particularly to a convertible leg/roller structure for 
supporting an easel or another object in either a stationary position or a 
movable position. 
Ser. No. 050,329, filed Mar. 18, 1987, now abandoned, discloses an 
expandable easel assembly for holding workpieces of many different sizes 
in a variety of different positions. This easel assembly has a pair of 
upright posts with horizontally extending base members at the lower ends 
thereof. The base members have ground engaging wheels and pads toward 
opposite ends thereof, and the easel assembly can be moved by tilting it 
to disengage the pads from the ground or floor and rolling it on the 
wheels. Moving the easel in this manner can be awkward, particularly when 
large workpieces are mounted on it, and there is a chance that it may fall 
when it is tilted. 
In order to improve stability, wheeled supporting structures have 
heretofore been provided with locks for the wheels or means for lifting 
the wheels off the floor or other supporting surface when the structure is 
in a stationary position. Examples of such structures are found in U.S. 
Pat. Nos. 2,354,906 and 3,534,974. With these structures, it is generally 
necessary to lift the entire structure in order to disengage or engage the 
wheels. 
It is in general an object of the invention to provide a new and improved 
structure for supporting an easel or another object in a stationary 
position or a movable position. 
Another object of the invention is to provide a supporting structure of the 
above character which overcomes the limitations and disadvantages of 
structures heretofore provided. 
Another object of the invention is to provide a supporting structure of the 
above character in which it is not necessary to raise the easel or other 
object supported thereby in changing between fixed and movable positions. 
These and other objects are achieved in accordance with the invention by 
providing a convertible leg/roller structure having a pivotally mounted 
leg movable between horizontal and vertical positions, a surface at one 
end of the leg for engagement with a supporting surface when the leg is in 
the vertical position, and a roller mounted on one side of the leg for 
engagement with the supporting surface when the leg is in the horizontal 
position. The leg pivots about an axle spaced equally from the portions of 
the leg and the roller which engage the supporting surface so that it is 
not necessary to lift the structure in order to move between the 
stationary and movable positions. A latch is included for locking the leg 
in at least one of the positions.

In FIG. 1, the leg/roller structure 11 is illustrated in connection with a 
horizontally extending leg or base member 12 of an object such as an easel 
assembly of the type shown in Ser. No. 050,329, filed Mar. 18, 1987, now 
abandoned. The base member has a generally rectangular cross-section, and 
it is fabricated of a rigid material such as wood, metal or a suitable 
plastic. 
Leg structure 11 includes a relatively short leg 13 which is likewise 
fabricated of a rigid material and has a generally rectangular 
cross-section. The inner end portion of leg 13 is pivotally connected to 
the outer end portion of base member 12 for movement about a horizontally 
extending axis between vertical and horizontal positions. The leg is shown 
in the vertical position in FIG. 1 and in the horizontal position in FIG. 
2. In this embodiment, a screw 14 secures the end portions of the leg and 
base member together and serves as a pin or axle for the pivotal 
connection. 
The outer end portion of base member 12 and the inner end portion of leg 13 
are dovetailed together so that the leg forms a substantially continuous 
extension of the base member in the horizontal position. In this regard, 
the base member and leg have tenons 16, 17 which are offset on opposite 
sides of the respective members and positioned side by side with the pivot 
pin extending through them. Base member 12 has a shoulder 18 adjacent to 
tenon 16, and leg 13 has a similar shoulder 19 adjacent to tenon 17. These 
shoulders serve as limiting abutments for the leg in the horizontal and 
vertical positions. When the leg is in the vertical position, the side of 
the leg abuts against shoulder 18, and shoulder 19 abuts against the lower 
side 21 of the base member. When the leg is in the horizontal position, 
the inner end 22 of the leg abuts against shoulder 18, and shoulder 19 
abuts against the outer end 23 of the base member. The corners 24, 26 of 
the tenons are rounded to clear shoulders 19, 18, respectively, as the leg 
is moved between the vertical and horizontal positions. 
A fixed pad 28 is mounted on the outer end of leg 13 for engagement with 
the floor 29 (FIG. 3) or another suitable supporting surface when the leg 
is in the vertical position. 
A caster 31 is mounted on the side of leg 13 which faces in a downward 
direction when the leg is in the horizontal position. The caster comprises 
a wheel or roller 32 which is rotatively mounted in a swivel frame 33 for 
engagement with the floor or other supporting surface when the leg is in 
the horizontal position. 
The dimensions of leg 13 and caster 31 are such that base member 12 and the 
easel or other object supported thereby are the same distance above the 
floor or other supporting surface whether the object is supported in a 
fixed position on the pad or in a movable position on the roller. 
Otherwise stated, the distance from screw 14 to the outer surface of pad 
28 is the same as the vertical distance from the horizontal plane of the 
pin to the lower periphery of the roller when the leg is in the horizontal 
position. The corner of pad 28 closest to wheel 32 is rounded as 
illustrated at 28a to facilitate movement onto and off of the pad without 
a rocking motion as this portion of the pad engages the floor. 
Means is provided for locking leg 13 in the horizontal position. This means 
includes a latch plate 36 which is pivotally mounted on a screw 37 for 
movement between locked and unlocked positions in a horizontally extending 
slot 38 in the end portion of base member 12. A corresponding slot 39 is 
formed in the end portion of leg 13 and is aligned with slot 38 when the 
leg is in the horizontal position. In this position, latch plate 36 can be 
swung into the slots to lock the leg into the base member, as illustrated 
in FIG. 2. The latch plate has a spring clip 41 which engages the upper 
surface of tenon 16 to hold the plate in the locking position. 
Operation and use of the leg/roller structure is as follows. The structure 
can be used to support an easel or other structure which needs to be moved 
from one stationary position to another. It is assumed that the easel or 
other object has a pair of horizontally extending base members similar to 
base member 12 and that a leg/roller assembly 11 is provided at each end 
of each of the base members. 
When the easel is to be used in a stationary position, legs 13 are moved to 
their vertical positions so that pads 28 engage the floor or other 
supporting surface and the legs and the easel rest upon the pads. 
To move the easel, legs 13 are swung to the horizontal position to bring 
rollers 32 into engagement with the floor or other supporting surface. As 
each of the legs is moved away from the vertical position, the roller 
mounted thereon engages the floor or supporting surface, and the load 
carried by the leg is transferred to the roller. As the leg continues its 
movement toward the horizontal position, the roller rolls on the floor and 
carries the load without appreciable deflection of the easel or the base 
structure. When the leg is in the horizontal position, lock plate 36 is 
pivoted into the slots and clip 41 is engaged with the upper surface of 
tenon 16 to hold the leg in this position. When the easel is resting upon 
the wheels, it can be rolled over the floor or other supporting surface as 
desired. 
To return to the stationary position, clip 41 is disengaged from tenon 16, 
and lock plate 36 is swung out of slot 39. Leg 13 is then swung in a 
downward direction, rolling on roller 32 as the load is transferred from 
the roller to the pad at the end of the leg. 
The embodiment illustrated in FIG. 4 is generally similar to the embodiment 
of FIG. 1, and like reference numerals designate corresponding elements in 
the two embodiments. In FIG. 4, caster 31 has been omitted for ease of 
illustration, but it will be understood that the caster is mounted on leg 
13 just as it is in the embodiment of FIG. 1. 
In the embodiment of FIG. 4, an additional slot 43 is provided for locking 
the leg in the vertical position. The additional slot is formed in the 
tenon portion 17 of the leg, and it is perpendicular to slot 39 so that it 
is aligned with lock plate 36 and slot 38 when the leg is in the vertical 
position. 
Operation and use of the embodiment of FIG. 4 is similar to that previously 
described. However, in this embodiment, leg 13 can be locked in the 
vertical position by engaging lock plate 36 with slot 43. 
The embodiment of FIG. 5 is generally similar to the other embodiments, and 
like reference numerals designate corresponding elements in this 
embodiment as well. 
The embodiment of FIG. 5 includes means for yieldably urging lock plate 36 
toward the locking position. This means includes a coil spring 46 mounted 
in a bore 47 in alignment with slot 38 in base member 12. A ball 48 at the 
inner end of the bore bears against a tang 49 at the inner end of the lock 
plate, and a set screw 51 is threadedly mounted in the bore behind the 
spring to adjust the amount of force exerted by the spring. 
As viewed in FIG. 5, spring 46 urges lock plate 36 to pivot in a clockwise 
direction about screw 37 toward the locking position. The lock plate can 
be disengaged from the slot or slots in leg 13 by rotating the plate in a 
counterclockwise direction against the force of the spring. When the plate 
is released, it is returned by the spring to the locking position. 
The embodiment illustrated in FIGS. 6-7 is generally similar to the other 
embodiments, and like reference numerals designate corresponding elements 
in this embodiment as well. The embodiment of FIGS. 6-7 differs from the 
others in that caster 56 has a shaft 57 on which swivel frame 58 is 
mounted. Shaft 57 is mounted on the side of leg 13 which faces in a 
downward direction when the leg is in the horizontal position, and frame 
58 swivels about an axis 59 perpendicular to the axis of the leg. In other 
words, frame 58 swivels about a vertical axis when the leg is in the 
horizontal position and about a horizontal axis when the leg is in the 
vertical position. A roller or wheel 61 is mounted on an axle 62 which 
extends between the arms of frame 58 in a direction perpendicular to axis 
59. 
In this embodiment, the roller axis (the axis of axle 62) is offset from 
the swivel axis (the axis of shaft 57), and the roller axis is positioned 
vertically beneath pivot screw 14 when the leg is in the horizontal 
position and the caster is positioned as shown in FIG. 6. The point of 
contact between roller 61 and floor 29 lies on an arc 63 which is centered 
about the axis of screw 14. The curved surface 28a on the pad at the end 
of leg 13 also lies on this arc to assure a smooth transition between the 
roller and the pad as the leg is moved between its horizontal and vertical 
positions. As the leg is moved toward the vertical position, caster 56 
swivels by gravity to the position shown in FIG. 7 to clear the underside 
of base member 12. 
In the embodiment of FIGS. 6-7, base member 12 and the load carried thereby 
are positioned the same distance above the floor whether the structure is 
resting upon roller 61 or pad 28. With the periphery of the roller and the 
curved surface of the pad lying on an arc centered about the axis of pivot 
screw 14, there is no rocking motion or change in height as the leg is 
moved between the horizontal and vertical positions and the load is 
transferred between the wheel and the pad. 
It is apparent from the foregoing that a new and improved convertible 
leg/roller structure has been provided for easels and other objects. While 
only certain presently preferred embodiments have been described in 
detail, as will be apparent to those familiar with the art, certain 
changes and modifications can be made without departing from the scope of 
the invention as defined by the following claims.