Conveyor shaft support assembly

An assembly for supporting the drive or idler shaft in an endless conveyor, such as an armored face or scraper chain conveyor, is provided. The assembly includes a pair of annular bearing housings having central bores for receiving the ends of an idler shaft carrying dual spaced inner, or single twin inboard sprocket rings. Each bearing housing includes a relatively wide integral support arm for insertion into a corresponding C-shaped bracket attached to the end face of the conveyor frame. Fasteners, such as dowel pins and bolts, are inserted into aligned vertical apertures formed in the cooperating support arms and brackets. In the mounted position, the bearing housings fully support the shaft ends independent of the conveyor frame sidewalls and thus are useful with conveyors having sidewalls spaced any distance apart. The independence provided by moving the bearing housings inward permits a shorter and consequently lighter shaft to be used and one that is less prone to deflection. Mounting the ends of the shaft in spaced bearing housings securely held in individual brackets reduces vibration, deflection and damage from shock loading. Positioning the bearings at the ends of the shaft also provides resistance for the twisting forces created by the heavy gauge chains, especially where dual spaced sprockets are present. Caps attached to the outer side of each bearing housing protect the rotating shaft ends and contain any lubricant present in the bores. Passages formed in the housings allow the bearings to be lubricated.

TECHNICAL FIELD
 The present invention relates generally to endless conveyors used to haul
 aggregate materials and, more particularly, to an improved assembly for
 supporting a conveyor drive or idler shaft independent of the sidewalls of
 the conveyor frame.
 BACKGROUND OF THE INVENTION
 In the underground mining of coal or other minerals, endless conveyor
 systems are used to transport the mined aggregate material won from the
 mine face to the surface for washing, dewatering, or other types of
 processing before it is ready for use. One type of conveyor commonly used
 is known as a stage loader. As well known in the art, the stage loader is
 a type of scraper chain conveyor that receives coal from an armored face
 conveyor as a part of a longwall mining machine and loads it onto a
 takeaway conveyor which eventually transports the coal to the surface. The
 scraper chain conveyor includes an upper deck supported by spaced
 sidewalls that define a feed path. To move the coal along this feed path,
 one or more heavy gauge chains are connected to pull a series of flight
 bars along the conveyor. A driven shaft having at least one sprocket is
 mounted at one end of the conveyor to drive the chain(s) and an idler
 shaft having a similar sprocket(s) is provided at the opposite end. Both
 ends of the conveyor include drive or idler support units for the
 respective shaft. These units typically include spaced support plates that
 project outwardly from the upper deck at the end of the conveyor frame.
 These support plates have semi-annular profiles that help in guiding the
 flight bars as the transition is made from the forward to the return run,
 or vice versa.
 In the past, drive or idler shafts were commonly supported in bearing
 housings carried directly in the sidewalls of the conveyor frame. An
 example of one such early proposal is found in U.S. Pat. No. 4,037,713,
 issued Jul. 26, 1977. This patent discloses a conveyor with spaced apart
 sidewalls, each having a recess for installing a bearing housing. The
 housings receive and provide rotational support for the ends of the
 respective drive or idler shaft.
 One significant limitation inherent in this "outboard" arrangement shown in
 this earlier patent (and others like it) is that access to the bearing
 housings is restricted. Furthermore, the conveyor frame for either the
 face conveyor or the stage loader (or other conveyor) is typically placed
 as close as possible to the mine face or other wall. This conserves space
 and, for an armored face conveyor, ensures that the coal won from the mine
 face falls onto the conveyor. This tight spacing further prevents the
 bearings from being easily reached for servicing on the side of the
 conveyor next to the face. Instead, the shaft and bearing housings
 together must be lifted upwardly out of the recesses in the conveyor
 frame. This is especially difficult in the confines of an underground
 mine. Such an arrangement makes not only servicing, but also inspection
 and/or lubricating the bearings extremely difficult and time consuming.
 A more recent approach can be found in U.S. Pat. No. 5,232,068, issued Aug.
 3, 1993, which discloses a conveyor frame having split sidewalls that
 contain bearing housings for rotatably supporting the ends of an idler
 shaft. As can be appreciated, the split sidewalls permit the drive or
 idler shaft to be more easily removed horizontally from the end of the
 conveyor, as may be necessary for servicing/repair or replacement.
 Additionally, a remote lubrication system is proposed to minimize wear on
 the shaft and lessen the frequency with which the shaft or bearings are
 replaced.
 The '068 patent also provides other features designed to overcome the
 limitations inherent in the support arrangement disclosed in the '713
 patent. However, it should be recognized that the shaft is still fully
 supported by the side walls of the conveyor frame. This means that the
 length of the shaft is dictated by the spacing of the sidewalls of the
 conveyor frame. In other words, because the shaft support is provided by
 the sidewalls of the conveyor frame, the shaft must be at least as long as
 the distance between the inner edges of these sidewalls. This not only
 increases the cost, but also prevents a drive or idler shaft from one
 conveyor from being interchanged with those used in different types or
 sizes of conveyors, as the spacing of the sidewalls of the conveyor frame
 frequently varies. Specialized shafts must be kept on hand for the many
 different types of armored face or scraper conveyors that may be used at a
 particular underground mining installation, which is obviously
 inconvenient and expensive. Moreover, if the shaft is damaged, worn out,
 or otherwise in need of replacement, significant and costly production
 downtime may result while a replacement shaft having a suitable length
 dimension is found or fabricated.
 In an effort to overcome these limitations, others have proposed
 arrangements where the drive or idler shaft is supported by separate
 bearing housings mounted inside, or "inboard," of the conveyor frame
 sidewalls. One example of such an arrangement is shown and described in
 British Patent Specification No. 2,156,943, owned by Fletcher Sutcliffe.
 In this proposal, spaced bearing housings each include narrow projecting
 studs inserted in corresponding recesses formed in a face plate of the
 conveyor frame. By tightening a nut on the threaded end of each stud, the
 peripheral surfaces of the bearing housings are brought into engagement
 with the corresponding ends of upper and lower support plates projecting
 from the conveyor frame. The bearing housings can be spaced apart for
 supporting the ends of the shaft (FIG. 5), brought inward with the
 sprockets moved to the ends of the shaft (FIG. 4), or combined in a single
 center bearing housing (FIG. 6).
 While this arrangement avoids the limitations created by supporting the
 shaft in the spaced sidewalls of the conveyor frame, it has several
 shortcomings. For example, the single stud mounting is very insecure and
 prone to failure in the harsh conditions and due to the tremendous forces
 that scraper chain conveyors are exposed to during normal operation. These
 forces include large deflection and twisting forces created by the
 rotation of the shafts as the heavy gauge chains are pulled or guided
 along by the sprockets. Over time, this tends to weaken or loosen the
 stud/nut fastener combinations securing the housings in place and could
 possibly lead to conveyor failure. It should also be appreciated that
 these fastener combinations are in a difficult place to reach below the
 upper surface of the conveyor. This complicates any preemptive servicing
 efforts and requires significant and costly production downtime in the
 event failure does occur.
 The deleterious effects of the twisting forces are especially problematic
 in the embodiment having dual outer sprockets carried on the ends of the
 drive or idler shaft (see FIG. 5 of the '943 patent). The coaction of the
 chains on such spaced sprockets tends to create an uneven loading
 condition that eventually allows the stud to pivot back and forth in the
 recess. To resist this twisting force, the '943 reference proposes
 capturing the respective ends of the shaft in recesses or slots formed in
 the sidewalls of the conveyor frame. Of course, although this may offer
 some resistance against the troublesome twisting forces, it again makes
 the shaft length directly dependent on the spacing of the sidewalls of the
 conveyor frame.
 Expressly recognizing the limitations of the above-described support
 arrangements, U.S. Pat. No. 4,953,692 to Stoppani et al. proposes a
 unitary central bearing housing mounted inboard of the conveyor frame
 sidewalls. Specifically, the '692 bearing housing includes a projecting
 nose for insertion in a receiving recess formed in the front of the
 conveyor frame. To seat this nose in the recess, an expansible fastener is
 inserted vertically through a single set of corresponding apertures
 extending through the nose and cross member. Once registered in the
 aligned apertures, expansion of the fastener is supposed to draw the
 bearing housing into engagement with the upper and lower portions of the
 cross member and hold it in this position.
 Although the housings in this proposal provide support for the shaft
 independently of the conveyor frame sidewalls, limitations similar to
 those described above for the Fletcher Sutcliffe proposal remain. For
 instance, the uneven loading on the shaft created by the chains riding on
 the dual outer sprockets eventually tends to cause the fastener to loosen,
 which can allow the nose to pivot in the receiving recess. This back and
 forth movement over time can destroy the tight seating engagement due to
 wear on the seating surfaces in the recess, and thus possibly lead to a
 conveyor failure. Furthermore, the center bearing housing arrangement
 proposed in this patent would not be suitable for use with drive or idler
 shafts having inner sprockets.
 Accordingly, a need is identified for an assembly for securely and reliably
 supporting a shaft in an endless conveyor of the scraper chain type that
 is commonly used to transport aggregate materials in underground coal
 mining. The assembly would support the shaft independent of the sidewalls
 that typically form a part of the conveyor frame. This independence would
 allow for shorter and consequently lighter shafts. Shafts could also be
 interchanged between conveyors having side walls spaced any distance
 apart, as long as this distance is greater than the length of the shaft.
 Additionally, a secure and reliable mounting for the shaft would enhance
 stability and resist twisting, deflection, and other large forces created
 as the chain(s) are pulled along or carried by the sprockets of the drive
 or idler shafts. However, the assembly would also allow the shaft to be
 easily accessed for maintenance, including dismounting for reversing or
 replacement, as may be necessary or desirable.
 SUMMARY OF THE INVENTION
 Therefore, keeping the above needs in mind, it is a primary object of the
 present invention to provide an assembly for supporting a shaft in an
 endless conveyor such as an armored face or scraper chain conveyor for
 hauling aggregate material that overcomes the above-described limitations
 and shortcomings of prior art arrangements.
 Another object of the present invention is to provide a shaft support
 assembly that provides secure and stable rotational support for the shaft
 independent of the sidewalls of the conveyor frame, thereby allowing for a
 shorter shaft to be used that is lighter and more resistant to deflection.
 Yet another object of the present invention is to provide a shaft support
 assembly having a pair of annular bearing housings that fully contain and
 support the ends of the shaft to resist twisting forces created by the
 chains being driven or pulled along by sprocket(s) carried on the shaft.
 Still a further object of the present invention is to provide a shaft
 support assembly including a pair of annular bearing housings and a shaft
 forming a unit that can be easily dismounted for reversing the ends of the
 shaft in order to increase the service life of the sprockets, or for other
 types of service, repair, or replacement.
 A further object of the present invention is to provide a shaft support
 assembly that includes a pair of annular bearing housings having central
 bores receiving and holding bearings that rotatably support each end of
 the shaft, said housings including removable caps for containing the outer
 end of each housing to protect the end of the rotating shaft and contain
 any lubricant present.
 Yet another object of the present invention is to provide a shaft support
 assembly with annular bearing housings that include a passage for allowing
 lubricant to be introduced to the bearings held in the central bore of the
 housing, thereby avoiding the need for dismounting the shaft and bearing
 housings to provide the regular lubrication, and thus minimize wear and
 maintain operational efficiency.
 Additional objects, advantages and other novel features of the invention
 will be set forth in part in the description that follows and in part will
 become apparent to those skilled in the art upon examination of the
 following or may be learned with the practice of the invention. The
 objects and advantages of the invention may be realized and obtained by
 means of the instrumentalities and combinations particularly pointed out
 in the appended claims.
 To achieve the foregoing and other objects, and according to the purposes
 of the present invention as described herein, an improved assembly is
 provided for supporting the drive or idler shaft in an endless conveyor.
 The endless conveyor can be an armored face conveyor, stage loader, feeder
 conveyor, or any other similar conveyor apparatus. For purposes of this
 description, the endless conveyor is a scraper conveyor having at least
 one heavy gauge chain that pulls flight bars along a feed path to haul
 aggregate material. At one end of the conventional scraper chain conveyor,
 a drive shaft carries one or more conveyor drive sprockets for driving the
 chain(s) along the conveyor feed path of the forward/operative run. The
 opposite end includes a non-driven idler shaft having a similar number of
 sprockets for reversing the chain(s) for guiding along the return run back
 to the drive sprocket(s). These chain(s) pull the flight bars along an
 upper deck defining the feed path contained on both sides by sidewalls
 that form a part of the conveyor frame. The following discussion of a
 preferred embodiment describes the shaft support assembly in use with an
 idler shaft on a scraper chain conveyor only. However, it should be
 understood that this description, in its broadest sense, is equally
 applicable to the driven shaft in a scraper chain conveyor or other
 similar types of conveyor apparatus.
 In the broadest aspects of the invention, the shaft support assembly
 includes a pair of annular bearing housings having a central bore for
 receiving the ends of the shaft. A bearing captured in each bore provides
 the desired rotational support for the shaft. Projecting from each housing
 is a relatively wide integral support arm. The support arm is adapted to
 fit closely in and abut with the inner surfaces of the corresponding
 support brackets. The support brackets are attached to the end face of the
 conveyor frame, they are kept inside of the sidewalls of the conveyor
 frame. These support brackets are preferably C-shaped and include upper
 and lower flanges and a cross web that together define an open yoke. This
 open yoke is sized to receive the support arm in a close tolerance fit on
 the top and bottom sides, and thus provide a tight seating engagement that
 is fully resistant to up and down relative movement. This engagement
 ensures that the desired full support for the shaft is provided
 independent of the sidewalls of the conveyor frame. Also, both the support
 brackets and the corresponding support arms are relatively wide to provide
 a greater contact surface on the top and bottom. The extra width of the
 support arms also provides superior resistance to the bending force that
 results from fully supporting the weight of the rotating shaft in a
 cantilevered fashion from the end of the conveyor frame.
 As should be appreciated, this independent mounting arrangement means that
 the length of the shaft is not dictated by the spacing of the sidewalls.
 This allows the shaft to be interchanged between conveyors having
 different types of frames without regard for the spacing of the sidewalls.
 The only requirements are that: (1) the shaft is shorter than the space
 between the sidewalls; and (2) the support brackets are attached to the
 end face of the frame. Thus, as noted above, the shaft support system of
 the present invention is readily adaptable to different types of
 conveyors.
 To hold the bearing housing securely in the mounted position projecting
 from the end face of the conveyor, vertically aligned apertures are formed
 in both the support arms and the upper and lower flanges of the
 corresponding brackets. These apertures receive fasteners or securing
 means, such as bolts/nuts and a dowel pin. Once inserted and registered in
 the aligned apertures, the fasteners positively secure the support arms in
 the brackets and ensure that the desired tight seating engagement is
 maintained. No side to side or up and down movement of the support arms is
 permitted by this arrangement, even if the shaft is subjected to extreme
 loading conditions.
 Additionally, it should be appreciated that the fasteners extend vertically
 downward through the aligned apertures, thus making the heads of the
 fasteners fully accessible from above. This easy access is particularly
 helpful when removing the shaft from the mounted position is necessary,
 such as for servicing, repair, or replacement. Another advantage of this
 easy access is that the shaft and bearing assemblies can be dismounted as
 a unit and reversed to provide even wear for the teeth on the sprockets.
 The support brackets are preferably mounted such that the topside of the
 upper flange is level with the upper deck of the conveyor. The heads of
 the fasteners are recessed in the upper flange of the support brackets to
 avoid interfering with the flight bars as they transition from the return
 to the forward run, or vice versa.
 It should now be recognized that once the bolts/dowel pin are registered in
 the vertically aligned apertures, full and stable support is provided for
 the bearing housings by the interaction between the brackets and support
 arms. In the operative position, the bearing housings are cantilevered
 from the end face of the conveyor frame, but the shaft is contained fully
 inside the conveyor frame sidewalls. The need for drawing the peripheral
 surfaces of the bearing housings into engagement with upper and lower
 support plates is eliminated. This is because full, stable, and secure
 support is provided for the shaft by the coaction of each of the support
 arm, bracket, and fastener combination.
 Bringing the bearing housings inward from the sidewalls, results in a
 significant reduction in the shaft length and a concomitant reduction in
 the weight of the shaft. The provision of a shorter shaft rotatably and
 fully supported at both ends by annular bearing housings also lessens the
 deflection loading caused by the tremendous forces typically acting on the
 drive and idler shafts in scraper chain conveyors, especially when dual
 inner sprockets are present. The enhanced stability provided by the
 bearing housings also reduces shaft vibration and the potential for damage
 from sudden shock loading. Additionally, placing the bearings at the outer
 ends of the shaft reduces the effects of the deleterious twisting or
 skewing forces generated by the dual chains as they are pulled along the
 feed path. Overall, a significant increase in shaft stability,
 reliability, and performance is realized using the novel shaft support
 assembly described above.
 Caps may also be installed on the ends of the annular bearing housings to
 provide additional protection for the rotating ends of the shafts and to
 contain any lubricant introduced to the central bore. A spacer mates with
 the inner face of the bearing housing to provide containment at the
 opposite end. Seals positioned adjacent the spacers inside the bore ensure
 that any lubricant is kept at the most effective location and cannot leak
 out of the housing.
 As should be realized, due to the hostile conditions present, regular and
 frequent lubrication must be provided for the bearings to minimize wear
 and maintain optimum operating efficiency. To ease the lubrication
 process, the annular bearing housings may also include passages for
 supplying lubricant directly to the bearings captured in the central bore.
 These passages allow bearing lubrication to be remotely applied, such as
 set forth in the '068 patent mentioned above. Grease fittings having a
 check valve can be provided to allow lubrication using a conventional
 grease gun. In either case, the ends of shaft are fully contained and any
 lubricant introduced remains in the central bore of the annular bearing
 housings to ensure effectiveness.
 Still other objects of the present invention will become apparent to those
 skilled in this art from the following description in which there is shown
 and described a preferred embodiment of this invention, simply by way of
 illustration of one of the modes best suited to carry out the invention.
 As it will be realized, the invention is capable of other different
 embodiments and its several details are capable of modification in
 various, obvious aspects all without departing from the invention.
 Accordingly, the drawings and descriptions will be regarded as
 illustrative in nature and not as restrictive.

Reference will now be made in detail to the present preferred embodiment of
 the invention, an example of which is illustrated in the accompanying
 drawing.
 DETAILED DESCRIPTION OF THE INVENTION
 Reference is now made to FIG. 1 illustrating an exploded perspective view
 of a preferred embodiment of the shaft support assembly 10. The assembly
 10 is shown in use on the idler unit positioned at one end of an endless
 scraper chain conveyor C or stage loader, which includes idler shaft
 assembly 12. As is well known in the art, the opposite end of the conveyor
 C includes a drive unit shown schematically in FIG. 5 and including a
 drive shaft support assembly 11 with drive shaft assembly 13 including a
 drive shaft 13a for driving one or more heavy gauge chains G. Flight bars
 E connected to these chains G are pulled along the conveyor C to haul
 aggregate material, such as coal won from the mine face.
 At the idler end, dual spaced inner sprockets 14 having a plurality of
 chain-engaging teeth 14a are carried on the idler shaft 12a of the shaft
 assembly 12. As should be appreciated, these sprockets 14 serve to guide
 the chains from the return run (note action arrow R in FIG. 4) below the
 conveyor frame F to the forward or operative run, or vice versa, depending
 on the direction in which the chain is being driven.
 The conveyor frame F includes spaced sidewalls S that interconnect with and
 provide support for the upper deck D (see FIG. 5). These sidewalls S also
 define the conveyor feed path and laterally contain any aggregate material
 being conveyed. Below the conveyor C, a base L with outboard legs is
 provided to support the conveyor C on the mine floor M.
 Projecting from the end of the conveyor are support plates U, each having
 an outwardly facing, semi-circular profile to guide the flight bars E as
 they transition around the end (see dashed line cutaway bar in FIG. 5). In
 FIG. 1, the sidewalls S and the support plates U are removed to provide a
 full view of the shaft support assembly 10. As should be appreciated, the
 drive end of the conveyor C includes a similar arrangement, the difference
 being that a drive motor is provided for driving the shaft.
 As best shown in FIG. 5, the shaft assembly 12 also includes a barrel 12b
 to provide spacing between the sprockets 14. A curved support projecting
 from the end of the conveyor frame F includes a removable upper deck
 extension P to assist the flight bar E in moving onto the upper deck D. As
 illustrated in FIG. 1, the support has an arcuate face corresponding to
 the shape of the shaft assembly 12, and more particularly, the barrel 12b.
 The plate extension P is attached by recessed bolts B, and thus is
 removable for replacement if necessary due to wear. In addition, chain
 strippers T project from the face of the conveyor frame F and fit into the
 respective annular inner channels 14b (see FIG. 5) formed between the
 split teeth of the sprockets 14. These strippers T ensure that the chains
 are lifted from the seated position between the teeth 14a as the sprockets
 14 guide the chain to the forward run.
 The assembly 10 includes a pair of annular bearing housings 16 for
 supporting the ends of the idler shaft assembly 12. As perhaps best shown
 in FIGS. 2 and 3, the bearing housings 16 each include a central bore 18
 adapted for receiving a bearing 22 for the respective ends of the idler
 shaft 12a. The bearings 22 are preferably tapered roller bearings that
 provide full rotational support for the shaft 12a.
 The bearing housing 16 is integrally formed with a relatively wide
 projecting support arm 20. Spaced support brackets 24 for receiving the
 respective support arms 20 are attached to the conveyor frame F. These
 brackets 24 are C-shaped and include upper and lower flanges and a cross
 web which together define an open yoke. The rear face of the cross web is
 attached directly to a cross member 26 of the conveyor frame F, such as by
 welding or other secure attachment methods known in the art. Optionally,
 as illustrated in FIG. 5, the sides of brackets 24 may be attached to the
 support plates U projecting from the conveyor frame F. It should be
 appreciated that this does not make the shaft support assembly 10
 dependent on the spacing of the sidewalls S or other fixed structures.
 This is because the spacing of the bearing housings 16 is defined by the
 location of the apertures in the brackets 24, and not the width of the
 brackets themselves. Thus, attaching the brackets 24 to the support plates
 U merely provides additional support and stability.
 The open yoke of the C-shaped brackets 24 is sized for receiving and
 holding the support arms 20 in tight seating engagement. Specifically, the
 brackets 24 contact the support arms 20 on the top and bottom such that
 they are positioned outwardly from the face of the conveyor frame F to
 provide direct rotational support for the shaft assembly 12. As should be
 appreciated, the close fit between the support arms 20 and the brackets 24
 provides stability as the rotating shaft assembly 12 is held in a
 cantilevered position from the end of the frame F. The close tolerances
 also prevent the support arms 20 from moving up and down in the brackets
 24, which reduces shaft vibration. As best appreciated by viewing FIGS. 1
 and 3 together, the support arms 20 are also relatively wide and thus
 resist bending forces created by the heavy gauge chain.
 To ensure that the support arms 20 are held securely in the seated position
 in the respective brackets 24 and cannot shift from side to side, each
 includes vertically aligned apertures 30 for receiving fastener
 combinations or other securing means. These fastener combinations can take
 the form of bolts 32 and at least one dowel pin 34 to facilitate initial
 alignment of the apertures. Specifically, in the most preferred
 embodiment, three vertically aligned apertures 30 are provided. The
 rearmost of the apertures 30 is adapted for vertically receiving a dowel
 pin 34 having an oversized head and a tapered upper neck. The two forward
 apertures 30 are adapted to receive shoulder bolts 32.
 Specifically during assembly, the dowel pin 34 is first inserted to bring
 the respective apertures 30 into alignment and to temporarily hold the
 bearing housings 16 in the brackets 24. Once registered in the rearmost
 vertically aligned apertures 30, each of the bolts 32 are inserted through
 the respective forward apertures 30 and the nut 32a is tightened onto the
 lower threaded end.
 Both the heads of the bolts 32 and dowel pin 34 are preferably recessed in
 the topside of the upper flange of each C-shaped bracket 24. As shown in
 FIG. 4, the recess for the bolts includes sufficient clearance to allow a
 socket to be inserted on the head. As should be appreciated, recessing the
 bolts 32 and dowel pin 34 prevents the heads from interfering with the
 flight bars as the transition is made from the return run to the forward
 run. A similar recess is provided in the lower flange to also allow a
 socket to be placed over the nuts 32a.
 As should be appreciated from viewing FIG. 1, the heads of the bolts 32 and
 the oversized head of the dowel pin 34 are fully accessible from above. By
 removing the respective nuts 32a and cotter pin 34a (if present) these
 fasteners 32, 34 may be lifted upwardly out of the respective apertures
 30. Once the fasteners are removed, the shaft assembly 12 and bearing
 housings 16 can together as a unit be pulled horizontally out of the
 spaced support brackets 24. This easy release feature is beneficial
 because it lessens the production downtime required for accessing the
 shaft assembly 12, such as for replacement/servicing.
 Another advantage of the easy release feature is that it allows the shaft
 assembly 12 to be quickly removed and reversed end over end to ensure that
 the components, including the teeth 14a on the sprockets 14, wear evenly.
 Specifically, it should be appreciated that the shaft 12a itself typically
 rotates only in one direction for a given period of time (as indicated by
 action arrow R in FIG. 4). The direction of rotation is dictated by the
 drive motor at the opposite end of the conveyor C. This eventually causes
 uneven wear between the leading and trailing faces on the teeth 14a. By
 removing the fasteners 32, 34, the shaft assembly 12 and bearing housings
 16 may be pulled from the brackets 24 as a unit. The entire unit can be
 flipped end over end to reverse the shaft assembly 12. As should be
 appreciated, so reversing the shaft 12a effectively converts the former
 trailing faces of the sprocket teeth 14a into leading faces. By reversing
 the ends of the shaft 12a from time to time, wear on the sprocket teeth
 14a is kept even, which extends the service life.
 This reversing operation is also simplified by the shorter length of the
 shaft 12a. The sides S do not have to be shifted or removed and the effort
 required to lift the entire unit is reduced due to the lighter weight. The
 bearing housings 16 can remain in position on the ends of the shaft 12a
 during this operation. The symmetrical nature of the bearing housings 16
 (see FIGS. 1 and 3) means that both can be interchanged between the
 brackets 24 while remaining fully functional and providing the desired
 tight seating engagement.
 The proposed support assembly 10 is also advantageous because it moves the
 bearing housings 16 outward toward the ends of the shaft assembly 12. This
 arrangement reduces the effects of the deleterious twisting forces
 generated by the dual chains as they travel over the spaced inner
 sprockets 14.
 In the preferred embodiment, caps 40 are installed on the outer ends of the
 annular bearing housings 16. These caps 40 provide additional protection
 for the ends of the rotating shaft 12a and serve to contain the lubricant
 present in the central bore 18.
 To provide the desired rotational support for the shaft 12a, a bearing 22,
 such as for example a tapered roller bearing, is installed and housed in
 the central bore 18 of the bearing housing 16. As illustrated in the
 partial cutaway view in FIG. 5, a bearing retainer 42 is secured to the
 end of the shaft 12a. A ledge 18a (see FIGS. 2 and 3) formed in the bore
 18 traps the bearing 22 at the opposite end.
 At the inner end of each bearing housing 16, a spacer 44 is provided for
 insertion in the bore 18 (see FIG. 5). The spacer 44 mates with the inside
 face of the bearing housing 16. Double seals 48 are positioned adjacent to
 the spacer 44 and against an annular shoulder 18b formed in the bore 18 to
 prohibit contamination of lubricant and provide a method of purging old
 lubricant.
 As should be appreciated, to reduce wear and maintain optimum operational
 efficiency, regular lubrication must be provided to the bearings. To ease
 the lubrication process, the annular bearing housings 16 also include
 passages 50 that allow lubricant to be supplied directly to the bearings
 22. In the preferred embodiment, an L-shaped passage 50 is formed in the
 medial portion of each bearing housing 16 (FIG. 3). This passage 50
 includes a feed orifice for receiving the end of the supply line of a
 lubrication system. The opposite end of the passage 50 opens into the
 central bore 18 (see FIG. 3). Of course, lubricant is forced through this
 passage 50. The radially extended passage 52 may also be provided in each
 housing 16 for pressure relief or other application and circulation of the
 lubricant. The outer bearing cap 40, spacer 44 and seals 48, ensure that
 the ends of shaft assembly 12 are fully contained and any lubricant
 introduced remains in an effective location in the bore 18. Of course, a
 grease fitting having a check valve and a nipple for receiving a
 conventional grease gun can be provided in one or both of the passages 50,
 52.
 In summary, many benefits and advantages can be realized by employing the
 shaft support assembly 10 of the present invention. In the operative
 position, the bearing housings 16 are held in a cantilevered fashion from
 the end face of the conveyor frame F. Support brackets 24 mounted to the
 end of the frame F provide full rotational support for the shaft assembly
 12 inboard of the sidewalls S. The tight seating engagement provided
 between the support arms 20 and support brackets 24 ensures that the shaft
 assembly 12 is held in a secure and stable position. Positioning the
 bearing housings 16 at the ends of the shaft assembly 12 better resists
 deflection caused by the tremendous forces typically acting on the drive
 or idler shafts in scraper chain conveyors. Of course, the shorter shaft
 assembly 12 is also lighter, which reduces the effort necessary during
 maintenance or removal. The enhanced stability of the bearing housings 16
 provided by the close tolerance fit between the top and bottom sides of
 the support brackets 24 and the support arms 20, reduces the vibration and
 twisting that would otherwise be experienced by the shaft assembly 12. The
 relatively wide support arms 20 also resist bending and flexing. Further,
 the easy release fastener combinations 32, 32a and 34, 34a are secured in
 vertically aligned apertures 30 extending through the support arms 20 and
 the brackets 24. These fastener combinations 32, 32a and 34, 34a also
 prevent any relative side to side movement. They are easily removed for
 dismounting the shaft assembly 12 and bearing housings 16 as a unit for
 servicing or repair (see the exploded perspective view of FIG. 1). Another
 advantage of this easy release feature is that it allows the shaft
 assembly 12 and housings 16 as a unit to be flipped end over end and
 reinserted in the brackets 24 to ensure even wear for the chain-engaging
 surfaces of the sprockets 14. This can accomplished without removing the
 annular bearing housings 16 from the ends of the shaft assembly 12,
 because the entire unit is symmetrical. To provide the desired continuous
 lubrication, the annular bearing housings 16 also include passages 50, 52
 communicating with the center bore 18. Caps 40, spacers 44, and seals 48
 provided at the ends of the bearing housings 16 ensure that any lubricant
 is contained and held at an effective location in the central bore 18, but
 allows purging of old lubricant.
 The foregoing description of a preferred embodiment of the protective
 system of the present invention has been presented for purposes of
 illustration and description. It is not intended to be exhaustive or to
 limit the invention to the precise form disclosed. Obvious modifications
 or variations are possible in light of the above teachings. The embodiment
 described above for supporting an idler shaft assembly 12 was chosen and
 described to provide the best illustration of the principles of the
 invention and its practical application to thereby enable one of ordinary
 skill in the art to utilize the invention in various embodiments and with
 various modifications as are suited to the particular use contemplated.
 All such modifications and variations are within the scope of the
 invention as determined by the appended claims when interpreted in
 accordance with the breadth to which they are fairly, legally and
 equitably entitled.