Abstract:
A lubrication apparatus lubricates the chain and trolley components of an overhead conveyor supported by a rail. Immediate lubrication is provided to such components without the need of a timer, thereby preventing any lubricant from being applied to non-target surfaces. The apparatus is mounted to the rail using hooks so that the integrity of the rail is preserved and relocation is simple. The apparatus can withstand an impact from a passing mis-aligned trolley. The apparatus can be adapted to lubricate chain and trolley components on different rail profiles, including an I-beam.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates generally to lubrication apparatus and method for an overhead conveyor system, and more particularly, to a lubrication apparatus method for an overhead chain and trolley conveyor system that selectively lubricates targets as they are presented. 
     Overhead “chain and trolley” conveyor systems are widely used in manufacturing and material handling operations. For instance, such systems can be designed to carry objects ranging from washing machines and car parts to poultry, and are used to move the objects through a plant in assembly-line like fashion. The conveyor system typically includes an elevated suspended guide rail, which is a beam having an I, T, L or other channel shape, and a series of interconnected wheeled trolley elements which hang from the beam, coupled to each other through a flexible chain-like linkage (“chains”). In the I-beam rail configuration, which is the most popular, the trolleys have a pair of bearing wheels which ride on the upper surface of the lower flange of the I-beam. The wheels extend from a yoke frame that girdles beneath and is centered on the web of the I-beam. The wheels are spaced from each other by a width that is just slightly greater than the thickness of the web of the I-beam, such that one wheel cannot slip off the lower flange, as the opposed wheel will encounter the web of the I-beam. The chain-like linkage is propelled, usually by a powered sprocket. In turn, the linkage moves the trolleys along the beam or guide rail. 
     In service, the trolley wheels and chains begin to wear over time. Points of wear include the bearing races within each wheel, and the joints between chain linkages. After a relatively short period of time, such as one year, the trolley and chains must be replaced to avoid the entire conveyor system binding and bringing the conveyor to a sudden halt. This frequent replacement can be an enormous expense for companies, especially if the trolley and linkages support very heavy objects, or if the conveyor system is lengthy. Lighter duty chain and trolley conveyors typically cost from $1 to $20 per foot, and may be used in plants having several miles of conveyors. Thus, the cost of replacing the chain and trolleys is very expensive, even without the costs associated with conveyor down-time and labor. It is very advantageous for companies to prolong the life of their overhead conveyors by regularly applying a lubricant thereto, as it is less costly than replacing the conveyor. This is especially true for the more expensive heavy-duty chains and trolleys. 
     Conventional lubrication systems for chain and trolleys have the disadvantage of applying a lubricant to an anticipated target such as a chain link or bearing race. For example, an upstream sensor will sense a particular target, and cause a lubricant to be released onto a downstream target. Because the targets are repetitive and equally spaced, it is anticipated that there will be a downstream target present to receive the lubricant when the upstream target is sensed. However, if there is a missing or damaged trolley, the lubricant will be released, but there will be no target present to receive it. Instead, the lubricant will either collect on the beam or drip down onto the conveyed object. In either case, lubricant will be wasted and applied to surfaces or objects other than a desired target. Furthermore, if the trolleys are sensed and only occur every few feet with several chain links in between, rather than a trolley for every chain link, then lubricant is not being applied to all of the chain links. 
     In many industries it is important to avoid having lubricant drip from the overhead conveyor onto the objects being conveyed. For example, in poultry processing plants, the conveyor system is used to carry a bird to and from the numerous work-stations as the bird is processed. Because the conveyed material is a food product, an essential performance criteria is that the conveyor and bird are kept clean of oil and other types of contamination. 
     Furthermore, mis-aligned trolleys cause not only misapplication of lubricant, but also hazards for the equipment that applies the lubricant, employees and/or equipment located below the apparatus. For example, if a trolley is missing a wheel and hanging out of alignment with the beam or rail, it can contact the lubrication apparatus and cause damage by bending the apparatus or knocking it free from the beam. The lubrication apparatuses need to withstand impact from mis-aligned trolleys. 
     In addition, lubrication apparatuses need to be easily replaceable and moveable for maintenance or other reasons. However, conventional lubrication apparatuses have the disadvantage of being attached to the beam in a manner that renders them impractical to relocate, and which lessens beam integrity. For example, holes are usually drilled into the beam so that the apparatus can be bolted thereon. Therefore, it is undesirable to relocate a conventional apparatus because new holes have to be placed in the beam each time such apparatus is moved. 
     SUMMARY OF THE INVENTION 
     Therefore, in view of the problems associated with the conventional type of overhead “chain and trolley” conveyor it is an object of the present invention to provide such an apparatus that will neither miss targets nor apply lubricant to objects other than the target. It is another object of the invention to provide a lubrication apparatus that can withstand impact from a mis-aligned trolley. It is yet another object of the invention to provide a lubrication apparatus that is can be readily relocated and has an attachment means that does not affect the structural integrity of the beam. 
     These and other objectives are met by the lubrication apparatus of the present invention. The lubrication apparatus is mounted to the beam using a mounting assembly. In one aspect of the invention, the mounting assembly uses hook members to attach the apparatus to the beam. 
     Depending on the configuration of the chain and trolley apparatus, there will be at least one bracket attached to the mounting assembly. The bracket or brackets hang adjacent the mounting assembly. Preferably, the brackets are pivotally attached to the apparatus so that they can readily move out of the way if a mis-aligned trolley hits the bracket. The brackets are further provided with flanges to direct any mis-aligned trolleys past the brackets without significant damage to the bracket. 
     At least one pump is attached to the apparatus, preferably to a bracket, the pump sending a lubricant to a nozzle that is directed to a target. Of course, one should realize that there may be more than one target, so a pump and nozzle is supplied for each separate target. 
     Lubricant is ejected from the nozzle when a photo-electric sensor attached to the apparatus senses the target. A control system is attached to the mounting assembly for controlling the air supply and pump operation. 
     In one aspect of the invention, an air supply is used to supply an air flow to each pump and to each nozzle to aid in ejecting the lubricant from the nozzle. 
     A method for lubricating a chain and trolley apparatus begins with positioning a lubricant dispersion device to project the lubricant at the target. Next, the target is sensed and lubricant is dispersed to the target. The dispersion of lubricant only occurs when a target is presented. 
     The present invention will be better understood from the following detailed description of the invention, read in connection with the drawings as hereinafter described. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an isometric view of the lubrication apparatus of the present invention mounted on an overhead conveyor; 
     FIG. 2 is a front elevation view of the lubrication apparatus of FIG. 1; 
     FIG. 3 is a partial isometric view of the lubrication apparatus of FIG. 1; 
     FIG.  4 . is an end view of the lubrication apparatus of FIG. 1, having flange portions cut-away to show the lower nozzle; 
     FIG. 5 is a schematic diagram showing the distribution of air, lubricant and power to various components of the present invention; 
     FIG. 6 is an isometric view of the nozzle of the present invention; 
     FIG. 7 is a cross-sectional side view of the nozzle seen in FIG. 6, further showing the inner pathways for air and oil; and 
     FIG. 8 is a schematic rear view of the control box. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention is directed to a lubrication apparatus that applies lubricant to passing targets on an overhead “chain and trolley” conveyor without misapplication. Thus, the apparatus only delivers lubricant when a target is present to receive it. While the present invention will be described hereinbelow with regard to an “I-beam” embodiment, it should be understood that various design modifications could be made to this embodiment without departing from the scope of the present invention. 
     The lubrication apparatus, generally referred to as  10 , is shown in FIG. 1 in relationship to the beam or guide rail  12  of the overhead conveyor  14 . The guide rail  12  is a suspended I-beam having an upper flange  16 , a lower flange  18 , and a web  20 . The overhead conveyor  14  has multiple trolleys  22 , which are linked in serial fashion to each other via a chain  24 . Each trolley  22  is fitted with a pair of wheels  26  which are journaled to a yoke  28  that girdles beneath the guide rail  12 . Some or all of the trolleys  22  convey one or more objects which hang from the yoke  28  by various means. As seen in FIG. 4, the wheels  26  are spaced so that they are separated by a gap  30  that is only slightly wider than the thickness of the web  20  of the guide rail  12 . Referring again to FIG. 1, the chain  24  is constructed from a series of links  32  coupled by a center link  34 . 
     As seen in FIGS. 2 and 4, the lubrication apparatus  10  has three main structural components, namely, a control box  36  and a pair of brackets  38 , which are attached to a mounting assembly  40 . Various other components are housed within the control box and attached to the brackets as described herein. 
     Apparatus  10  can be used to lubricate overhead “chain and trolley” conveyors of various sizes. Conveniently, apparatus  10  is modular and only the size of the brackets  38  and mounting assembly  40  changes accordingly. Therefore, the same control box  36 , can be used for conveyors  14  of any size. 
     Control box  36  generally houses the control system for apparatus  10 . Referring to FIG. 8, the control system is comprised of an electrical power supply unit  37 , and several solenoids  39  used to distribute air to nozzle members and pumps as described herein. Also housed in control box  36  is an air manifold  41  and a lubricant manifold  43  for distributing the air and lubricant supplied from exterior sources, and two air-pressure regulators  105 ,  107 , further described herein. Though the general arrangement of these components is not critical, it is preferable that the lubricant manifold  43  be oriented so that the lubricant supplied thereto is equally and simultaneously distributed to the lubricant lines  11 . For example, this would be the case if the manifold was uniformly shaped (i.e. a parallelpiped), and the manifold floor and outlets were lying in horizontal and parallel planes. In the event of an accidental lubricant leak, lubricant manifold  43  is preferably located beneath the electrical components to prevent lubricant from wetting such components, as the lubricant can flow out of control box  36  through a hole (not shown) in the control box floor. This arrangement not only prevents one from having to clean up a mess inside control box  36 , but prevents a possible short circuit as well. 
     Referring now to FIGS. 1 and 2, control box  36  is attached to mounting assembly  40  so that it is positioned on top of the beam or guide rail  12 . Mounting assembly  40  is generally constructed from a pair of spaced end plates  42  connected by two spacers such as bars  44 , and a pair of pivot rods  46 . Both bars  44  and rods  46  are positioned so that their longitudinal axes are parallel. Preferably, end plates  42  are constructed from metal bar stock, and are held in a parallel spaced relation to provide support for both control box  36  and brackets  38 . Furthermore, end plates  42  are equivalent in dimension so that when they are mounted to rail  12 , control box  36  is stable with respect to rail  12 , and the movement of brackets  38  is not hindered. As will be described herein, brackets  38  pivot about the longitudinal axes of rods  46 . Therefore, the dimensions of end plates  42  are such that the plate edges  48  do not interfere with the movement of brackets  38 . 
     Preferably, each rod  46  is connected to end plates  42  so that they are rigidly attached within apertures  50  formed in plates  42 . Each rod  46  has an end block  52  at each end. End blocks  52  rotate about the rods  46 , and provide surfaces  54  to which the brackets  38  may be attached. End blocks  52  are manufactured so that they can rotate completely around rods  46  to which they are attached. This will provide for a maximum range of movement for brackets  38 . 
     Apparatus  10  is secured to rail  12  without having to drill holes therein. This attachment is achieved by a plurality of hooks  56 . Hooks  56  are generally rectilinear members having an arcuate notch  58  on one face. Hooks  56  are pivotally attached to end plates  42  with fasteners  60  so that they can selectively engage upper flange  16 . When apparatus  10  is positioned on rail  12  so that it is aligned thereto, hooks  56  are pivoted inwardly toward the rail web  20  until they engage upper flange  16 , and fasteners  60  are then tightened. Preferably, fasteners  60  have hexagonal or other tool-accepting heads which require only a hex key and/or an open-ended wrench for fastening. 
     A pair of stop screws  62  are located on each side of the bars  44  between end plates  42 . Stop screws  62  serve to provide an adjustment of the angle at which brackets  38  come to rest. Preferably, each pair of stop screws are equally adjusted so that the inside surface  64  of bracket  38  simultaneously comes to rest against the two stop screws  62  to which it is adjacent. Stop screws  62  are adjusted so brackets  38  are in an optimal position with respect to the passing trolleys  22 , i.e. so that passing trolleys  22 , if properly aligned, do not make contact with the brackets  38 , but not to hinder movement of the brackets if a mis-aligned trolley is encountered. 
     Referring now to FIG. 4, brackets  38  are shown to have a profile that generally follows the contour of the trolley  22  and chain  24 . Bracket  38  supports the components that sense and supply lubricant to various targets on the trolley  22  and chain  24 . Thus, the closer these components are to the targets, the better the application of lubricant thereto. To easily achieve this bracket profile, it is preferable that brackets  38  are formed from sheet metal using a stamping and bending process. As will be evident herein, the sheet metal is desirable not only for ease of manufacture, but for its strength and light weight. 
     Because the trolleys are moving past brackets  38  at several feet per minute, a hazard is created for the brackets  38  of apparatus  10 . Specifically, as indicated above, if a trolley is somehow mis-aligned and does not fit between the profiles of brackets  38 , it will hit bracket(s)  38  with substantial force. Such force could be great enough to bend or tear off bracket(s)  38 , or even cause the entire apparatus  10  to fall off the guide rail  12 . Therefore, flanges  66  are provided on each side of brackets  38 . Flanges  66  are angled away from the bracket&#39;s inner surface  64  to thereby guide the mis-aligned trolley between the brackets  38 . Flanges are provided on each side of brackets  38  so that apparatus  10  can be mounted or the conveyor can move in either direction without consequence to the brackets. 
     As indicated, brackets  38  are hinged about rods  46  so that if a mis-aligned trolley  22  hits a flange  66 , the bracket  38  is able to swing out of the path of trolley  22 . Thus, the flanges  66  serve to redirect forces applied to bracket  38  in the conveyor or “machine” direction, to that of a perpendicular direction. It is this force transmission that initially causes the brackets  38  to swing outwardly. Referring to FIG. 3, one should note that any fasteners or components that project from the bracket inner surface  64  should be rounded to provide a similar force transmission as the flanges  66 , and to prevent the passing trolley from catching an edge and damaging bracket  38 . 
     Referring now to FIGS. 1 and 2, various components are attached to the brackets  38  for sensing or delivering lubricant to targets on the overhead conveyor. These components are target specific, and generally include a pump  68  having a nozzle  70   a  or  70   b  (generally referred to as nozzles  70 ) and a photo-electric sensor  110  or  112  associated therewith. “Target specific” means that there is a separate pump  68  and nozzle  70  for each target. The independence of the pumps and nozzles ensures rapid, precise and consistent delivery of lubricant to each target. Furthermore, if a lubricant line gets plugged, the pump  68  will force the plug out of its corresponding single nozzle; if there were only one pump used for several nozzles, lubricant would flow from the unplugged outlets and the plug would not be forced out of the system. Moreover, as will become apparent, these target specific components allow for precise lubrication without the use of timers. 
     Each pump  68  is attached to the outer surface of a bracket  38 . Preferably, pump  68  has the characteristic of being relatively compact and lightweight, and not prone to dripping, clogging or forming air pockets in the line between pump  68  and corresponding nozzle  70 . One pump having such characteristics is the PURGEX® pump manufactured by the Oil-Rite Corporation of Manitowoc, Wis. This pump is described in U.S. Pat. No. 5,984,652, which was issued to Gruett et al. on Nov. 16, 1999. To avoid the formation of air bubbles in pump  68 , it is preferable to position the pump outlet  74  in an upward position. Gravity will force the lubricant downward, and any bubbles upward so that they can flow out of the pump. Such air bubbles will be forced out through nozzle  70  without consequence. Another particular advantage of the PURGEX® pump is that is has an “evacuation seal.” This evacuation seal is created by a slight vacuum created within the PURGEX® pump, such vacuum causing any excess lubricant left at the outlet of nozzle  70  to be drawn back into the nozzle. This is an advantage in that excess lubricant does not drip downward onto the floor or a conveyed object. 
     A nozzle  70  is connected to each pump outlet  74  by a lubricant line  76  so that the lubricant can be delivered to a corresponding target. The primary targets in the overhead conveyor of FIG. 2 are (1) the wheel bearing race  78  and (2) the pins  80  connecting the chain links  32  and center links  34 . Therefore, in the preferred embodiment, on each bracket  38  there is a first nozzle  70   a  positioned in an upper panel  82  and aimed at the bearing race  78 , and a second nozzle  70   b  is positioned in a middle panel  84  and aimed at the pins  80  through a window provided in the lower panel  92 . In particular, on one bracket  38  there is a nozzle  70   b  aimed to the left so that it lubricates the first pin  61  behind the leading edge  63  of the center link  34  (see FIG.  2 ), and on another bracket  38  there is a nozzle aimed to the right so that it lubricates the second pin  65  connected to the same center link  34  (see FIGS.  2  and  3 ). 
     As seen in FIGS. 2 and 3, the nozzles  70   a  and  70   b  are preferably mounted in slots so that their position can be adjusted. Specifically, the nozzle  70   a  attached to bracket upper panel  82  can be horizontally positioned in a slot  86 , and the nozzle  70   b  attached at bracket middle panel  84  can be horizontally positioned in a slot  88 . A window slot  90  is provided in bracket lower panel  92 . Window slot  90  is longer than slot  88  to accommodate nozzle  70   b.    
     Referring now to FIGS. 6 and 7, the nozzle  70  is described. Though nozzle  70   a  is depicted in FIGS. 6 and 7, one skilled in the art will realize that even though the outer structure of the nozzles  70   a  and  70   b  are different, the inner structure is the same for both nozzles  70   a  and  70   b.  Therefore, the nozzle will be generically referred to in the following description as nozzle  70 . 
     Nozzle  70  is constructed of a main body  73  generally having a lubricant passage  75  and an outer, concentric air passage  77 . Initially, body  73  has a cylindrical bore  75  running the length of the body  73 . At each end of the body  73 , two counterbores are provided: a first counterbore  79  generally defining the lubricant inlet, and a second counterbore  77  generally defining the air outlet. At the opposite end of body  73 , a third counterbore  83  is provided that is concentric with respect to second counterbore  77 . 
     At the first counterbore  79 , the lubricant inlet  79  is tapped to accommodate a fitting  81  that is connected to a lubricant line  76  (FIG.  2 ). Referring to FIG. 7, at the side of body  73 , there is an air inlet  89  that communicates with counterbore  77 . Air inlet  89  is also tapped to accommodate a threaded fitting  91  that is connected to air supply line  99  (see FIG.  2 ). 
     To keep the air and lubricant from mixing within nozzle body  73 , a tube member  93  extends from the first counterbore  79  through the length of body  73 . Tube member  93  is connected to body  73  with a press fit. It is important that tube member  93  be concentric with respect to bore  77 . If the longitudinal axis of tube member  93  does not correspond with the longitudinal axis of counterbore  77 , the air flowing through bore  77  will cause the lubricant to spray in a direction that is not parallel with the longitudinal axis. Preferably body  73  is constructed of brass, tube member  93  is constructed of stainless steel, and fittings  81 ,  91  are constructed of nylon. 
     As seen in FIGS. 2 through 4, the nozzle  70   b  body is a rectilinear block  71  rather than a cylinder shape so that it fits more easily against the bracket middle panel  84 . Block  71  accommodates the interior structure of nozzle  70  as described in the preceding paragraphs, and is attached by a fastener such as carriage bolt  94 , described in more detail below. Block  71  has a top, a bottom and four sides. The outlet of nozzle  70   b  is located at a side of block  71 . A hole (not shown) extends from the top to the bottom of block  71  to accommodate the fastener. Therefore, the top of block  71  is mounted to bracket  38  at slot  88 . This arrangement allows one to horizontally and vertically direct nozzle  70  through slot  90  for precise aim at the desired target. 
     Referring to FIGS. 3 and 4, the lower nozzle  70   b  is preferably attached to the middle panel  84  by a carriage bolt  94 . A carriage bolt generally has a rounded bolt head, a four-sided or “square neck”  95  directly underneath the bolt head, and a threaded shank extending from the neck  95 . Neck  95  is what slides in slot  88 , and the tightening of a nut  95   a  onto the shank of bolt  94  prevents bolt  94  from spinning. This safely and conveniently allows one to adjust the lower nozzle  70   b  by applying a single wrench to the bolt shank and nut  95   a  located at the outer surface of bracket  38 . Having to access anything at the inner surface of bracket  38  would require conveyor  14  to be stopped. 
     Referring to FIG. 1 lubricant is supplied to apparatus  10  from an outside source at a port  72 . Lubricant distribution lines  11  run from the manifold  43 , through an aperture (not shown) located in the floor of control box  36 , out to an inlet  98  at each pump. As previously described, lubricant outlet lines  76  run between the pump outlets  74  and nozzles  70 . FIG.  5 . shows schematically how the lubricant supply  102  is distributed to four pumps  68  and their corresponding nozzles  70 . 
     Pressurized air is also supplied to the apparatus  10  from an outside source  104 . Referring to FIGS. 1 and 8, air is supplied to a port  96 . An optional air filter  97  may be provided to filter the supplied air at the port  96 . The air is supplied at a pressure of approximately 150 psi, and is distributed to a pair of pressure regulators  105 ,  107 . These regulators  105 ,  107  are used to selectively decrease the pressure of air going to nozzles  70  and pumps  68 . Referring also to FIG. 3, the pressure adjustment is made by turning the appropriate knurled knob  108  to adjust the regulator  105  or  107 . Referring now to FIG. 8, a branched line  13   a  inside control box  36  connects port  96  to regulators  105  and  107 . Branched line  13   b  connects regulator  107  to the solenoids  109  and  111 . The air from solenoids  109 ,  111  goes to lines  100  (only one line  100  shown) which supplies air to the pumps at inlet  98   b  (shown in FIG.  1 ). Line  13   c  connects regulator  105  to solenoid  113 . The air from solenoid  113  goes to a manifold  41 , where it is distributed to air supply lines  99 , which are connected to the nozzles  70 . A pair of pressure gages  106  corresponding to each regulator are visible at the outside of control box  36  so that the operator can determine the air pressure resulting from the regulator  105 ,  107  adjustment. Lines  13   e  connect each regulator  105 ,  107  to gages  106 . 
     As will be described more fully herein, when an electrical signal is received from the photo-electric sensors  110  and  112 , the solenoids  109  and  111  permit air to flow to pumps  68  so that the lubricant can pass therethrough. 
     As seen in FIG. 5, the electrical power is supplied to the sensors  110 ,  112  and solenoids  109 ,  111  and  113  from the power supply  115 . As soon as electrical power is supplied to solenoid  113 , the air flows to the nozzles  70 . There is a constant flow of air through the nozzles  70  at all times so that when the lubricant is released form the pump to nozzle  70 , is transported more quickly to the target without a lag time. 
     The lines communicating between components on bracket  38  and control box  36  can enhance the assembly and operation of the apparatus  10 . Preferably, the air and lubricant supply lines are flexible to allow bracket  38  to move freely. This also helps to ease assembly and any adjustment made to the position of nozzle  70 . Furthermore, it is preferred that the air lines  100  are different in color and clarity than the lines carrying lubricant. For example, the air lines may be opaque and a blue color, whereas the lubricant lines may be clear and of no color. This allows an operator to easily distinguish the lines and see if there are any air bubbles or blockage in the lubricant lines. Finally, it is preferable that the lubricant outlet lines  76  are smaller in diameter than the distribution lines supplying lubricant to pump  68 . This difference in diameter reduces the compression of gases within the lubricant, and ensures a more rapid delivery of lubricant to the nozzle  70 . 
     Referring now to FIG. 2, independent photo-electric sensors  110  and  112  are used to sense whether a target is presented for lubrication. One skilled in the art will realize that other sensors can be used, such as a proximity sensor or the like. Each sensor  110  and  112  is comprised of two components, an infra-red light source and a receiver. Each sensor  110  component is located directly across from one another in bracket upper panel  82  so that the light beam produced by light source is received by the receiver. Likewise, each sensor  112  component is located directly across from one another in lower panel  92 . Power is supplied to the light source from power supply  115  (see FIG.  5 ). The system operates as a closed system. When the beam is received by the receiver, the pumps  68  do not activate; when the beam is interrupted by a target, the pumps  68  send lubricant to the nozzles  70 . 
     One skilled in the art will realize that placement of the various sensors and nozzles will vary depending on the trolley and chain configuration. Furthermore, the direction in which apparatus  10  is mounted onto rail  12  is affected by the direction in which the conveyor moves. The apparatus  10  is mounted to the rail so that when conveyor  14  is moving in machine direction  118 , sensor  112  is positioned so that it is downstream of the nozzles  70   b  in either bracket  38 . If the machine direction  118  were reversed, apparatus could be turned 180 degrees and remounted to rail  12 . 
     As seen in FIG. 2, brackets  38  have two sets of apertures  120 ,  122  photoelectric sensor  112  is mounted in one set of apertures). With two sets of apertures  120 ,  122 , bracket  38  can be mounted to either side of apparatus  10 . This is an advantage in that assembly is less complicated and there is no need to order a specific replacement bracket  38  in case of bracket damage. Larger aperture  120  is a “window” for sensor  112 , and smaller apertures  122  are for the fasteners used to attach sensor  112  to bracket  38 . One skilled in the art will further realize that apertures  120 ,  122  could instead be elongated vertical slots to allow the vertical adjustment sensor  112 . This is true for all other apertures that accommodate sensors  110  or  112 . Such vertical adjustment is desirable when there is a sagging chain, as will be described herein. 
     In operation, apparatus  10  is secured to rail  12  using hooks  56 . Apparatus  10  can be mounted to a horizontal, inclined or arcuate rail  12 . As mentioned previously, there is no need to drill holes or otherwise affect the integrity of the beam or rail  12  during such attachment. 
     Apparatus  10  is mounted so that the regulator knobs  108  are easily accessible. This requires only the repositioning of the sensors  110  and  112 , and nozzles  70   a  and  70   b  on each bracket  38 , as described previously. After apparatus  10  is mounted onto rail  12 , the aim of nozzles  70   a  and  70   b  is adjusted so that lubricant will hit specific targets immediately after their corresponding sensors  110 ,  112  are activated. Specifically, each trolley nozzle  70   a  is directed to lubricate the bearing race at point  126 . Chain nozzle  70   b  in one bracket  38  will be directed to lubricate pin  80  at point  128  (see FIG.  2 ), and chain nozzle  70   b  located in the opposite bracket  38  will be directed to lubricate pin  80  at point  130  (see FIG.  3 ). Because the machine direction  118  is moving right to left, the lubricant is applied to point  128  after it has moved past its corresponding nozzle  70   b,  and the lubricant is applied to point  130  before it moves past its corresponding nozzle  70   b.    
     Sensors  112  are aimed so that the light source emanating from the sensor remains interrupted during the entire time it takes center link  34  to pass sensor  112 . This prevents premature firing of the pumps. In a case where the chain tends to sag, the sagging is taken into account when aiming the sensors  112  so that the infra-red light cannot transmit over the top of center link  34  as it passes. 
     It should be noted that because there is no timing involved between the sensing and lubrication of the targets, the chain  24  can move at varying speeds and still be properly lubricated at the desired targets. Only an adjustment of the nozzles  70  or sensors  110 ,  112  is required. 
     Once the sensors  110 ,  112  and nozzles  70   a  and  70   b  have been properly positioned, the air and lubricant supply is connected. The air pressure is adjusted at regulators  105  and  107  by adjusting knobs  108 . In the embodiment shown in the drawings, regulator  105  corresponds to the nozzles  70 , and regulator  107  corresponds to the pumps  68 . Preferably, air is supplied to the pumps  68  at a pressure of 80 to 100 psi, whereas air is supplied to the nozzles  70  at a much lower pressure, approximately 20 psi. The pumps  68  require a higher pressure to aid in the quick disbursement of lubricant. The nozzles  70  require only enough air pressure to aid in the quick delivery of the lubricant to the target without atomizing the lubricant. Furthermore, the air flow from the nozzle  70  helps to prevent dripping. 
     Apparatus  10  is now ready for operation. As each trolley  22  and chain  24  move between the brackets  38  of apparatus  10 , sensors  110  and  112  will be triggered so that an electrical signal is sent to solenoid  109  or  111 . Solenoid  109  or  111  will send an air pulse to its corresponding pumps  68 , which in turn causes lubricant to travel from pumps  68  to nozzles  70 . The air supplied to nozzle  70  and the air pressure supplied to pump  68  is high enough to project the lubricant from the nozzle  70  to a target. 
     While the overhead conveyor lubrication apparatus of the present invention has been described and illustrated hereinabove with regard to specific embodiments, it should be understood that various design modifications could be made to these embodiments without departing from the scope of the present invention. For example, the invention could be used with rail shapes other than an I-beam. Furthermore, the inner bearing race of the trolley could be lubricated by aiming a nozzle at the inner race thorough a hole in the top flange of the I-beam. Therefore, the present invention is not to be limited to these specific embodiments, except insofar as such limitations are included in the following claims.