Track system

A track system for a slidable tray of a dental instrument delivery system includes a stationary slide guide member, a movable slide body member and a floating bearing assembly interposed between these members in coupling arrangement.

RELATED APPLICATIONS 
This application is related to U.S. Patent Application Ser. No. 890,652, 
filed Mar. 20, 1978, concurrently herewith. The related application 
discloses and claims a novel dental instrument delivery system with a 
movable upper tray surface. The present application discloses and claims a 
track assembly particularly usefule in connection with that system. The 
applications are commonly assigned, and the inventors of the aforesaid 
Ser. No.890,652, are co-inventors of this application. The disclosure of 
the aforesaid related application is hereby incorporated by reference to 
the extent that it is applicable hereto. 
BACKGROUND OF THE INVENTION 
1. Field 
This invention pertains to dental instrument delivery systems and 
specifically provides a track assembly for mounting an upper tray in 
removable relation to the instrument deck of such a system. 
2. State of the Art 
Dental delivery systems which include an upper tray surface atop an 
instrument deck are in common use. It has recently been proposed to mount 
the upper tray surface in slidable relation to the deck so that the tray 
may be moved either to the right or left of the deck and be positioned in 
cantilever relation with the deck. Because the deck is generally 
positioned in the proximity of (often directly over) a dental patient, it 
is essential that the mounting mechanism for the tray have a pleasing, or 
at least unimposing appearance. 
Available track systems, such as are used in mounting drawers and sliding 
doors, for example, are not suitable for cantilever support. Moreover, 
these and other track systems used in connection with cabinetry and the 
like, typically provide only limited travel, usually in a single direction 
with respect to a fixed end of a stationary track. 
SUMMARY OF THE INVENTION 
The present invention provides a track system especially adapted to support 
a tray surface in cantilever relation from opposite sides of the 
instrument deck of a dental instrument delivery system. The track system 
of this invention provides stable support for a loaded tray moved to 
either side of the deck so that substantially the entire tray is suspended 
from only a short coupled length of trachage. 
The claimed trackage system comprises three components. A first member, 
called a slide guide is mounted atop the instrument deck, preferably 
within a recess provided for that purpose. Ideally, the slide guide 
extends the entire width of the deck, terminating at, or very near, its 
opposite side edges. Cosmetic considerations require that this member 
should not ordinarily project beyond either side edge. 
A second member, called a slide body, couples, in slidable relation, with 
the first member, and is fixed to the bottom of a tray. This member should 
extend across substantially the entire width of the tray, but must 
terminate sufficiently short of the tray edges to be inconspicuous. If the 
slide guide is mounted within a recess in the instrument deck, the recess 
must be sufficiently wide to accommodate the slide body. Moreover, the 
depth of the recess with respect to the track components must be selected 
to provide clearance between the upper deck surface and the bottom of the 
tray. 
The third member is a floating bearing assembly, including a pair of guide 
elements adapted to fit between the slide guide and slide body on opposite 
sides of the guide. Each guide element loosely contains rolling bearings, 
preferably ball bearings. The travel of the slide body with respect to the 
slide guide is limited by the length of the floating bearing assembly. 
Accordingly, it is important that this assembly be structured within a 
short length, preferably about two inches, but in no event longer than 
will permit eighty percent (80%) of the length of the sliding tray to 
project beyond either of the side edges of the deck. 
A sliding tray mounted in accordance with this invention will measure 
somewhat over a foot in length, exclusive of its handles. A typical such 
tray, about 13 inches in length can be suspended by the claimed trackage 
system in stable condition with as much as 101/2 inches of its length 
cantilevered beyond either edge of the instrument deck.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENT 
A dental instrument delivery system, indicated generally by the numeral 11, 
includes an instrument deck 12. A groove 13 formed in the top of the deck 
contains a slide guide 14 fixed firmly in position as shown. 
A sliding tray 15 is attached to a slide body 16, shown upside down in FIG. 
3. The slide body 16 mates with the slide guide 14 within the groove 13, 
providing only slight clearance between the tray 15 and the deck 12 as the 
tray is moved selectively from cantilever suspension overhanging a first 
edge (FIG. 1) to a similar position overhanging the opposite edge (FIG. 2) 
of the deck 12. In either position, the tray 15 is located behind but well 
to the side of the array of hand piece hangers 17 arranged along the front 
edge of the deck 12. Of course, the tray may be positioned at any location 
intermediate the extremes illustrated by FIGS. 1 and 2, if desired. 
Referring specifically to FIG. 3, a floating bearing assembly, designated 
generally 20, includes a pair of bearing guides 21. These guides 21 may be 
of metal, but are preferably of a stiff, wear-resistant, non-abrasive 
material, such as nylon. A steel ball bearing 22 is carried within a hole 
23 at each of each guide 21. The thickness of the guides is less than the 
diameter of the balls 22, the guide 21 serving mainly to maintain the 
spacing of the balls 22, thereby to avoid binding of the slide guide 14 
and slide body 16. For example, a typical guide 21 for use with slide 
components 14, 16 approximately one foot in length will be about two 
inches long and about 1/8 inch thick and will retain a pair of balls 22 
about 1/4 inch in diameter spaced about 11/2 to about 13/4 inches from 
each other. 
It is essential that the guide 14 and body 16 members slide easily in 
either longitudinal direction. It is also essential that even in the 
extreme extended positions of FIGS. 1 and 2, the slide body 16 be firmly 
supported by the slide guide and held against substantial movement with 
respect to the guide 16 in any direction other than longitudinal. The 
floating bearing assembly, in combination with the special configurations 
of the members 14, 16, are thus critical to this invention. 
The slide body 16 receives the slide guide 14 between its side walls 30, 
with slight clearance, on the order of 0.05 to 0.1 inch on each side of 
the guide 14. A rail 31 extends approximately the entire length of the 
guide 14 along its upper surface 32 (shown upside down in FIG. 3 for 
clarity). This rail 31 is received by a matching slot 33 in the slide body 
16. Somewhat less clearance, typically about half that provided at the 
side walls 30, is provided for the interfitting of these elements 31, 33. 
The slot 33 is somewhat deeper than the height of the rail 31, and the 
slide guide 14 is somewhat thicker than the depth of the channel 35 within 
which it is received. Accordingly, any direct contact between the slide 
guide 14 and slide body 16 is limited to the unslotted portions of the 
upper inner surface 36 of the body member 16. 
The ball bearings 22 travel within a pair of square tubular chambers 
defined by slots 37 along the edge of the slide guide 14 and matching 
slots 38 in the side walls 30 of the slide body 16. Travel of the assembly 
20 is limited by roll pins 40 at opposite ends of the slide guide 14, 
while travel of the slide body is limited by roll pins 41 at the ends of 
the slide body 16. Corresponding roll pins 40, 41 are driven into bores 42 
sufficiently to clear each other as the slide body 16 is moved across the 
slide guide 14, but a portion of each of these pins is left protruding 
into the slots 37, 38, respectively, to act as stops against the bearing 
guides 21. 
The ball bearings 22 traveling in the chambers defined by the opposed slots 
37 and 38, assure smooth travel of the tray 15 with very little frictional 
resistance. Equally important, however, when the tray 15 is cantilevered, 
as shown in either FIG. 1 or FIG. 2, the bearings 22 taken up 
substantially all of the clearance between the members 14, 16, assuring a 
rigid lateral coupling. Moreover, with the bearing assembly 20 and the 
roll pins 40, 41 installed, the individual balls 22 couple the members 14, 
16 together so that the slide body 16 may not be lifted from the slide 
guide 14. 
It is to be understood that the embodiments of the invention above 
described are merely illustrative of the application of the principals of 
the invention. Reference herein to details of the illustrated embodiment 
is not intended to limit the scop of the claims which themselves recite 
those features regarded as essential to the invention.