Multi-level chain conveyor with load by-pass at selected levels

A lift conveyor for conveying loads from one level to another comprises a first and second pair of offset endless chains trained over sprockets which guide the chains through their travel in a substantially parallel and spaced-apart relationship. The sprockets are rotatably driven by a motor, and load-carrying connectors connected to the chains define horizontal platforms between levels for carrying the loads and are bendable during their travel over the sprockets. By-pass stations are provided at each floor adjacent the chains which are selectively operable to by-pass any given floor. The by-pass station includes a lift table and a hydraulic device for raising and lowering the lift table. A horizontal roller conveyor on the lift table receives the loads and conveys them to a storage terminal, or when the table is raised in a by-pass mode, serves to re-load the load back onto the lift conveyor for lifting and unloading to another floor.

FIELD OF THE INVENTION 
The present invention relates to multi-level chain conveyors and is 
particularly related to such conveyor systems for lifting loads from one 
station to another station. More particularly, this invention relates to a 
multi-level chain conveyors for loading and unloading at different 
vertical stations, with preselected load by-pass capabilities at different 
or preselected levels. 
BACKGROUND OF THE INVENTION 
Vertical lifts and conveyors are commonly used to move various loads from 
one level to another, usually higher level. Various types of such lifts 
and conveyors have been used in the past and are described in several 
patents and publications. For example, U.S. Pat. No. 1,736,011 describes 
an automatic unloading elevator adapted to unload at different levels. In 
another patent, i.e., U.S. Pat. No. 3,024,891, the patentee describes a 
continuous vertical lift having endless flexible chains carrying 
horizontal platforms. The platforms are rigid in their horizontal carrying 
positions but bend during their return to a loading position and hence 
occupy a minimum of space. More recently, U.S. Pat. No. 4,465,177 which 
issued to Wolfgang C. Dorner on Aug. 14, 1984 describes an elevator for a 
conveyor system which receives a load from the conveyor and delivers it to 
a second conveyor at a different level. 
Other patents which are representative of the different types of conveyors 
heretofore used include U.S. Pat. Nos. 1,057,934; 1,829,317; 1,856,262; 
2,931,524; 3,184,039; 3,557,940; 3,593,862; 3,631,963; 3,735,853; 
4,039,070 and 4,130,193. While these patents are representative of the 
variety of load conveyor systems used in the past, they are by no means 
exclusive. 
One of the disadvantages of the vertical conveyor systems which have 
heretofore been employed is that they do not provide load by-pass 
capability at each or preselected levels. As it will be seen from the 
ensuing description of the present invention, the provision of load 
by-pass capability for a lift conveyor enhances its usefulness and 
versatility since loads can be delivered to, or by-pass, any level at the 
control of the operator while maintaining a continuous operation. 
It is therefore an object of this invention to provide a multi-level 
conveyor for moving loads from one level to another level. 
It is also an object of this invention to provide a continuous multi-level 
load conveyor for moving loads from one level to another level with 
by-pass provision at the different levels. 
It is further object of this invention to provide a continuous chain 
conveyor for moving loads from one level to another level wherein the 
conveyor system uncludes load by-pass assembly at each or preselected 
level. 
The foregoing features and advantages of the present invention will be 
appreciated from the ensuing detailed description of the invention and the 
accompanying drawings. 
SUMMARY OF THE INVENTION 
The objects of the present invention are achieved by a multi-level lift 
conveyor provided with load by-pass stations which are selectively, and 
automatically, operable for either unloading the load at any level and 
conveying it away to a terminal, or for by-passing that floor and 
reloading it onto the lift conveyor for unloading to another floor. The 
conveyor system of this invention comprises a lift conveyor for lifting 
loads in a multi-level framework from one level to another. The lift 
conveyor includes a first and second pair of offset and spaced apart 
endless chains which are trained over corresponding sprockets. The 
sprockets are rotatably driven by a motor and serve to maintain the chain 
substantially parallel and spaced apart during their travel. 
Connector units serving as load carriers in the form of a platform are 
connected between the chains. The load-carrying connectors or platforms 
are substantially horizontal during their travel between the levels but 
are bendable over the various sprockets. 
Each level is provided with a roller conveyor and a lift table which, after 
the load is unloaded at that level, serves to either convey the load away 
to the desired terminal or re-load it back onto the lift conveyor thereby 
by-passing that level and lifting the load to another level. The lift 
table includes a hydraulic lift and a pivotably connected arm which can be 
automatically triggered by the hydraulic cylinder in order to raise or 
lower the lift table depending on whether or not the level is in a by-pass 
mode.

DETAILED DESCRIPTION OF THE INVENTION 
Referring to the drawings, with particular reference first to FIG. 1, the 
conveyor system of the present invention generally comprises an offset 
pair of endless chains trained over a plurality of sprocket wheels 
(rollers) throughout their travel. Only the first pair of chains is shown 
in FIGS. 1-5 and the second pair of chains is arranged and spaced as the 
first pair of chains and travels in exactly the same manner but is 
separated from the first pair. The two pairs of chains are connected by 
connector units which span the distance between the two chains of each 
pair and serve to support the load in its travel as hereinafter described 
in more detail. The conveyor system of the present invention and its 
operation will now be described with reference to a 4-floor conveyor with 
the load being loaded on the first floor and unloaded on the third or 
fourth floor, the second floor serving as a load by-pass station. Of 
course, any floor may serve as the by-pass station, if desired, by 
triggering or activating the by-pass mechanism at that floor as will be 
explained below. 
Thus, referring to FIG. 1, a load 100 such as a box or a carton is shown 
placed on a skid 101 which is advanced by a roller conveyor 103 in the 
direction of the arrow A. As the load 100 is advanced in this direction, 
it will be picked up by the flexible load carrying connector 105 which 
together with the pairs of offset chains 107 and 109 and the second pair 
of chains, travel over the sprocket wheel (roller) 111 which rotates in 
the same direction as the arrows A. In the drawings, while the offset 
chains are shown and designated as 107-109, as it was previously stated, 
in the views shown in FIGS. 1-5, only the front pair of the offset chains 
107 and 109 are visible, there being a corresponding pair of offset chains 
107a and 109a which are not seen in these views but shown in FIG. 6. 
The load-carrying connectors are generally platforms which are 
substantially horizontal between levels but bendable over the sprockets 
during the chains movements. Such platforms are known in the art and 
described, for example, in U.S. Pat. No. 3,679,074, the disclosure of 
which is incorporated herein by reference. Similarly, there are 
corresponding sets of sprocket wheels at the rear of those sprocket wheels 
which are also not shown in the drawings for simplicity of illustration of 
the conveyor system. The pairs of offset chains 107 and 109 are trained 
over the sprocket wheels (rollers) 113 and 115, respectively, as they 
advance upward while the load 100 on the skid 101 is being supported 
during such upward travel by the flexible chain connector 105. As is more 
clearly shown in FIG. 6, the flexible connector chain 105 is generally a 
flexible platform adapted to travel over the sprocket wheels after 
disengagement of the load and skid from the connector. Thus, as the load 
is lifted in the direction of the upward travel of the offset chains 107 
and 109 see arrow B), the chains will travel over the sprocket wheels 117 
and 119 whereafter the chain 107 travels over and around the sprocket 
wheel 121, upwardly toward and over the sprocket wheel 123 where it joins 
the chain 109 and then over sprocket wheel 125. Simultaneously, chain 109 
has travelled over and around the sprocket wheels 119, 123 and 125. 
Meanwhile, the load connector 105 has advanced to the position shown in 
FIG. 1 above sprocket wheel 125, ready to pick up the load 100 from the 
second floor by-pass station. When the load 100 is lifted to the second 
floor and reached the unloading position on the second floor, it is 
unloaded onto the lowered by-pass station, whereafter, the by-pass station 
is triggered to become operational, lifting the load to thereby cause the 
load to by-pass the second floor for unloading on the next higher floor. 
Thus, when the second floor is in the by-pass mode, the skid is unloaded 
onto a roller conveyor 127 which is supported by a lift table 129 when 
both the roller conveyor and the table are in the "down" position (see 
FIG. 2). The roller conveyor 127 consists of a plurality of rotatably 
driven or freely rotatable cylinders aligned in tandem and supported on 
parallel support members. The roller conveyor 127 is in the down position 
when the lift mechanism of the lift table 129 is in the down position. 
Thus, as shown in FIGS. 1 and 3, the lift table 129 is provided with a 
hydraulic cylinder 131 and a connecting arm 133. In the by-pass mode, the 
hydraulic cylinder 131 is activated (by a suitable means not shown) 
thereby raising the arm 133 and thus the lift table 129 to a level higher 
than the flexible load connector 105, which is now being carried between 
the pair of offset chains 107 and 109. With the roller conveyor 127 
travelling in the direction of the by-pass arrow C, the load skid 101 
carrying the load 100 will engage the flexible load connector 105 as is 
shown in FIG. 4. Once the load is fully on the load connector 105 and off 
the roller conveyor 127, the hydraulic cylinder 131 is deactivated to 
thereby retract the arm 133 and thus lower the table 129 to its initial 
level. 
The load connector 105 now carrying the load 100 travels upward as before, 
with the chains 107 and 109 travelling over the sprocket wheels 135 and 
137 and continue their upward travel, over the sprocket wheels 139 and 141 
until the load reaches the third floor (see FIG. 1) where, in the 
illustrative description herein, it is in the unloading mode. As the chain 
107 and 109 reach the third floor, the load connector 105 delivers the 
front of the skid 101 to the roller conveyor 143 which is of the same type 
and general construction as the roller conveyor 125 and which travels in 
the direction of the arrows D. A lift mechanism similar to that on the 
second floor is also provided on the third floor, however, the lift 
mechanism is in a retracted position so that the lift table is at the same 
level as the roller conveyors. In this mode, as the load is discharged onto 
the roller conveyor on the third floor, the load continues to advance in 
the direction of the arrows D to a storage terminal or some other facility 
(not shown). 
If it is desired to lift the load for discharge onto the fourth floor, the 
lift mechanism on the third floor will be activated to become operational 
as a by-pass floor as in the case of the second floor. Thus, in accordance 
with the present invention, loads may be conveyed vertically from one level 
to several levels and, selectively by-pass any level by providing a 
conveyor system as herein described with load by-pass means stationed at 
any desired level. 
After discharging the loads at the highest level (fourth floor in FIG. 1) 
depending on the number of levels in the conveyor system, the offset 
chains 107 and 109 are shown in FIG. 1 to travel over the sprocket wheels 
145 and 147 and back, in the direction of the arrow E, toward the bottom 
sprocket wheel 149 and once again over the sprocket wheel 111 thereby 
completing the loop which defines the endless chain conveyor. 
As it can be seen from the foregoing description, the conveyor system 
described herein can be used to discharge the load at each level. If the 
level is preselected to be a by-pass station, the load will be lifted for 
re-loading onto the conveyor. Thus, the by-pass consists of an unloading 
operation at a given level followed by a reloading operation at that 
level. For example, and once again referring to FIG. 1, a load which is 
placed on the conveyor on the first floor may be by-passed twice, once at 
the second floor and a second time on the third floor until it is finally 
unloaded on the fourth floor. This may be accomplished by providing a 
by-pass mechanism at each level and automatically triggering this by-pass 
to reload the load after it has been unloaded at that level. 
The present invention therefore provides a lift conveyor with preselected 
by-pass stations uniquely suitable for multi-level loading and unloading 
operations. While the invention has been described with certain degree of 
particularity, it is apparent from the description herein that many 
changes and modifications may be made which are obvious to those skilled 
in the art. Such changes and modifications are nevertheless within the 
scope of this invention.