Abstract:
A linear motion guide unit makes application of lubricant around rolling elements at the turnaround passage to accomplish securely the maintenance-free lubrication over a prolonged period of time. 
     A lubricant reservoir plate of porous compact is composed of a lubricant reservoir major body impregnated with lubricant and an applicator nose which is different in the molded density from the lubricant reservoir major body. The lubricant reservoir plate impregnated with lubricant is composed of the lubricant reservoir major body installed in a recess made in the end cap and the applicator nose extends through a slot of the turnaround passage to expose itself to the turnaround passage to make application of lubricant around the rolling elements.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to a linear motion guide unit composed of an elongated guide rail and a slider designed to move on the elongated guide rail relative to the guide rail through more than one rolling element. More especially, the present invention relates to a linear motion guide unit in which the slider has a lubricant reservoir plate of porous compact. 
       BACKGROUND OF THE INVENTION 
       [0002]    Conventionally, the linear motion guide units are composed of an elongated guide rail or guide shaft, and a slider which fits over or conforms to the guide rail or guide shaft for sliding movement relative to the guide rail or guide shaft through more than one rolling element of ball or roller which is allowed to circulate in an endless manner through an endless circuit made up of a load-carrying race defined between the guide rail and the slider, a return passage extending in the slider and turnaround passages lying at opposite ends of the slider. With the prior linear motion guide units with lubricating members, while lubrication between the race and the rolling elements has been ensured with periodic application or resupply of lubricant, advanced linear motion guide units recently become required to meet with needs of maintenance-free operation for lubrication over a prolonged interval of time for cost savings of maintenance for lubrication in the machinery and/or installation. 
         [0003]    In Japanese Laid-Open Patent Application No. 2007-100 951 which is a commonly-assigned senior application, there is disclosed a linear motion guide unit having lubricant resupply means in which application of lubricant around the rolling elements is done at the turnaround passage to make the lubrication system simpler than ever in construction, along with maintenance-free for steady and positive lubrication. With the prior linear motion guide unit constructed as stated earlier, the end cap has an opening extending from a recess on the outward end surface to the turnaround passage and a lubricant reservoir plate of porous compact impregnated with lubricant fits into the recess on the outward end surface of the end cap. The lubricant reservoir plate has an applicator nose extending through the opening in the end cap to form at the extremity thereof in part the circular wall of the turnaround passage to expose itself to come into engagement with the rollers rolling through the turnaround passage to feed the rolling elements with lubricant through the applicator noses of the lubricant reservoir plate, thereby making application of lubricant around the rollers while rolling through the turnaround passage. 
         [0004]    We has developed a linear motion guide unit with a lubricating plate which can be easily attached and/or removed without making an alternation in basic specifications disclosed in Japanese Laid-Open Patent Application No. H10-205 534 which is also a commonly-assigned senior application. With the linear motion guide unit recited earlier, the lubricating plate is disposed between a spacer and an end seal and attached to a carriage of a slider to travel relative to a guide rail in a way making sliding contact with raceway grooves on the guide rail. The lubricating plate is made of sintered resinous material of porous compact impregnated with oily lubricant. The sintered resinous material is produced after finely powdery synthetic resin has been compacted in a mold under pressure together with the application of heat. The lubricating plate is divided into a denser part and a coarse part which are bound together with a covering. 
         [0005]    In another Japanese Laid-Open Patent Application No. 2012-154 438 which is a commonly-assigned senior application, there is disclosed a linear motion guide unit in which lubrication for the rolling elements is carried out in a turnaround passage in an end cap and an applicator nose to come into touch with the rolling elements has a molded density greater than in a lubricant reservoir plate to ensure a more longer lubrication-life for proper and steady lubrication, with accompanying sustainable maintenance-free condition for lubrication. The lubricant reservoir plate of porous compact impregnated with lubricant fits in a recess on the end cap to expose the applicator nose integral with the lubricant reservoir plate to the turnaround passage through an opening cut in the turnaround passage to make application of lubricant around the rolling elements by use of the applicator nose. With the lubricant reservoir plate, the applicator nose of the porous compact has the molded density of from 0.60 g/cm 3  to 0.70 g/cm 3 , and the lubricant reservoir plate of the porous compact has the molded density of from 0.40 g/cm 3  to 0.60 g/cm 3 . 
         [0006]    With the prior linear motion guide unit constructed as stated earlier, application of lubricant around the rolling elements is carried out in the turnaround passage in the end cap. More especially, the rolling elements while rolling through the turnaround passage in the end cap come into engagement or contact with the applicator nose of the lubricant reservoir plate and in doing so the lubricant is fed around the rolling elements by means of applicator nose of the lubricant reservoir plate. With the linear motion guide unit constructed as stated earlier, more lubricant than a required and sufficient amount for rolling contact of the rolling elements and the races continues applied around the rolling elements in the beginning phase of operation. However, after lubricant contained in the lubricant reservoir plate has diminished down to a preselected level, the lubricant continues reducing with a substantially fixed reduction rate per unit distance. This means that lubricant contained in the lubricant reservoir plate, because more consumed at the beginning phase of operation, gets less as compared with an ideal phase where lubricant would ever-decrease from the beginning with the fixed reduction rate per unit. That comes into question the maintenance-free interval gets less. 
         [0007]    Advanced linear motion guide units recently have become required to meet with needs of maintenance-free operation for lubrication over a prolonged interval of time for reduction in number of maintenance-free steps and reduction in consumed amount of lubricant aiming at saving of resources and environmental impacts. With the linear motion guide units in which the application of lubricant around rolling elements is carried out in the turnaround passage, accordingly, there has been required development of the maintenance-free construction in which the lubricating member is allowed to store lubricant as much as possible as well as lubricant rids itself of more application at the beginning phase of operation to make sure of smooth application of adequate amount of lubricant around the rolling elements application over a prolong period of time. 
       SUMMARY OF THE INVENTION 
       [0008]    The present invention has for its primary object to overcome the major challenges as stated earlier, and to provide a linear motion guide unit in which application of lubricant to the rolling elements is carried out in the turnaround passage in the end cap while the rolling elements roll through the turnaround passage. To this end, a lubricating member of porous compact installed in the end cap is composed of a lubricant reservoir plate and an applicator nose. The end cap has a through-hole opening to the turnaround passage and the applicator nose extends into the through-hole so as not to protrude into the turnaround passage. Thus, the applicator nose comes into engagement at the edge thereof with the rolling elements while rolling through the turnaround passage without caught by the applicator nose. As the result, the lubricating member constructed as stated earlier helps realize the maintenance-free operation for application of lubricant around the rolling elements as well as prolong the lubrication life. 
         [0009]    The present invention is concerned with a linear motion guide unit; comprising an elongated guide rail having widthwise opposed sides each of which has a first raceway surface extending lengthwise of the guide rail, a slider having a second raceway surface extending in opposition to the first raceway surface on the guide rail to define a load-carrying race between the first raceway surface and the second raceway surface, and more than one rolling element rolling through the load-carrying race to move the slider relative to the guide rail; 
         [0010]    wherein the slider includes a carriage, end caps, a lubricant reservoir plate of porous compact, and end seals, the carriage having the second raceway surface and a return passage extending in parallel with the second raceway surface, the end caps being fastened on forward and aft end surfaces of the carriage, one to each end surface, and provided with a turnaround passage to join together the load-carrying race and the return passage, the lubricant reservoir plate being impregnated with lubricant and installed in the end cap to come into engagement with the rolling elements to make application of the lubricant around the rolling elements while rolling through the turnaround passage, and the end seals being installed on the end caps; 
         [0011]    wherein the lubricant reservoir plate is composed of a lubricant reservoir main body installed between the end cap and the end seal to fit in a recess formed in the end cap, and an applicator nose which fits in an opening made in the lubricant reservoir main body and extends into a through-hole to communicate with a slot in the turnaround passage; 
         [0012]    wherein the applicator nose is constituted with a basal part and a nose part raised above the basal part to form a circular flat area lying around the nose part, the circular flat area being larger in transverse section than the through-hole to come into abutment around the nose part against the end cap to keep in place the applicator nose, and the nose part being integral with the basal part to fit into the opening in the lubricant reservoir main body to expose an end face of the nose part to the turnaround passage; and 
         [0013]    wherein a molded density of the porous compact is less in the lubricant reservoir main body than in the applicator nose whereby as the lubricant soaked in the applicator nose is consumed, the lubricant previously held in the lubricant reservoir main body moves to be resupplied into the applicator nose with capillary action. 
         [0014]    The porous compact to provide the lubricant reservoir plate is made of finely powdery ultrahigh molecular weight synthetic resin, which is first subjected to compacting and the resulting compact is subsequently sintered at elevated temperature to provide open-porous or open-cellular texture whose pores or cells preserved among fine particles are open each other through interstices or channels. The lubricant reservoir main body has a molded density less than 0.60 g/cm 3  and the applicator nose has a molded density in the range of from 0.60 g/cm 3  to 0.70 g/cm 3 . Moreover, the porous compact is made of polyester polyurethane foam of three-dimensional skeleton texture which is molded while compressed to ¼˜ 1/20 under compression to provide open-porous or open-cellular texture. As an alternative, the porous compact is made of fibrous material including nonwoven cloth, felt and cotton. 
         [0015]    The nose part of the applicator nose is raised above the basal part to form a circular flat area around the nose part. The circular flat area after the lubricant reservoir plate has fit into the recess in the end cap comes into abutment around the nose part against a wall surface around the recess in the end cap to keep the nose part against protrusion into the turnaround passage. As an alternative, the nose part of the applicator nose is raised above the basal part to form a circular flat area around the nose part, and the circular flat area after the lubricant reservoir plate has fit into the recess in the end cap comes into abutment around the nose part against a stepwise wall in the opening in the turnaround passage to keep the nose part against protrusion into the turnaround passage. 
         [0016]    With the linear motion guide unit constructed as stated earlier, the slot open to the outside circular surface of the turnaround passage in the end cap has an elliptic figure elongated in a moving direction of the rollers. Moreover, the nose part of the applicator nose is made in a solid extending from the circular flat area to a tip face to fit into the elliptic slot. 
       ADVANTAGEOUS EFFECTS OF THE INVENTION 
       [0017]    With the linear motion guide unit of the present invention, the lubricant reservoir plate is composed of the lubricant reservoir main body and the applicator nose. The applicator nose is constituted with the basal part which fits into the opening in the lubricant reservoir main body, and the nose part which at the end face thereof comes into the rolling elements while they roll through the turnaround passage. The basal part is made larger in transverse section than the slot to form the circular flat area lying around the nose part to come into abutment around the nose part against the wall surface of the recess in the end cap major body to keep in place the applicator nose, thereby to restrain the nose part from protrusion into the turnaround passage. Thus, the end face of the nose part comes into engagement with the rolling elements to make the application of lubricant around the rolling elements without causing any obstacle to the movement of the rolling elements, thereby making sure of smooth movement of the rolling elements in the turnaround passage. Moreover, the molded density of the porous compact is made less in the lubricant reservoir main body than in the applicator nose to increase the amount of lubricant impregnated in the lubricant reservoir main body. As the lubricant soaked in the applicator nose is consumed, the lubricant previously preserved in the lubricant reservoir main body is allowed to move to be resupplied into the applicator nose with the capillary action. With the lubricant reservoir plate according to the present invention, the lubricant reservoir main body and the applicator nose are constituted separately from each other to have the molded density different from one another, which could help them manufacture with a desired molded density and inspect with ease. The lubricant reservoir plate may be assembled by only insertion of the applicator nose into the opening of the lubricant reservoir main body. With the lubricant reservoir plate, in addition, the lubricant reservoir main body, because of made of inexpensive material, may be manufactured with less amount of costly material of high molded density. With the lubricant reservoir plate constructed according to the present invention, the uniform amount of lubricant may be supplied around the rolling elements all the time. That is, more application at the beginning phase of operation is controlled to preserve high the remaining rate of lubricant in the lubricant reservoir plate even after prolonged operation of the slider. As a result, the lubrication life of the lubricant reservoir plate is prolonged to realize the maintenance-free operation of the linear motion guide unit. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]      FIG. 1  is a fragmentary and partially cutaway view in perspective showing a preferred embodiment of a linear motion guide unit according to the present invention. 
           [0019]      FIG. 2  is a view in transverse section of the linear motion guide unit of  FIG. 1 , the view being taken on the planes of line II-II of  FIG. 1 . 
           [0020]      FIG. 3  is a view in longitudinal section showing a circulating circuit made in a slider in the linear motion guide unit of  FIG. 1 . 
           [0021]      FIG. 4  is an exploded view in perspective showing an end cap, lubricant reservoir plate and an end seal in the linear motion guide unit of  FIG. 1 . 
           [0022]      FIG. 5  is a view in front elevation of a version of the lubricant reservoir plate of  FIG. 4 . 
           [0023]      FIG. 6  is a view in bottom elevation of the lubricant reservoir plate of  FIG. 5 . 
           [0024]      FIG. 7  is a view in front elevation to show a major body of lubricant reservoir plate of  FIG. 5 . 
           [0025]      FIG. 8  is a view in bottom elevation showing the lubricant reservoir plate major body of  FIG. 7 . 
           [0026]      FIG. 9  is a view in front elevation showing an applicator nose for the lubricant reservoir plate of  FIG. 5 . 
           [0027]      FIG. 10  is a view in bottom elevation of the applicator nose of  FIG. 9 . 
           [0028]      FIG. 11  is a view in front elevation showing the linear motion guide unit of the present invention, but in which the end seal is removed from the linear motion guide unit. 
           [0029]      FIG. 12  is a view in front elevation of the end cap in which the lubricant reservoir plate is combined in preparation for assembly with linear motion guide unit shown in  FIG. 11 . 
           [0030]      FIG. 13  is a view in bottom elevation showing the end cap for the linear motion guide unit of the present invention. 
           [0031]      FIG. 14  is a view in front elevation of the end cap of  FIG. 13 . 
           [0032]      FIG. 15  is a view in rear elevation showing the end cap major body and the lubricant reservoir plate in the linear motion guide unit of the present invention, in which a spacer part is removed from the end cap. 
           [0033]      FIG. 16  is a view in section, the view being taken along the plane of line XVI-XVI of  FIG. 15 . 
           [0034]      FIG. 17  is a view in section, the view being taken along the plane of line XVII-XVII of  FIG. 15 . 
           [0035]      FIG. 18  is a view in front elevation showing another version of the lubricant reservoir plate in the linear motion guide unit of the present invention. 
           [0036]      FIG. 19  is a view in section showing another version of the lubricant reservoir plate in the linear motion guide unit of the present invention, the view being taken along the plane of line XIX-XIX of  FIG. 18 , and. 
           [0037]      FIG. 20  is a view in section showing a further another version of the lubricant reservoir plate in an area corresponding to the view taken along the plane of line XIX-XIX of  FIG. 18 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0038]    The linear motion guide unit of the present invention is adapted for use in any relatively sliding components in machinery as diverse as various assembling machines, robotic machines, semiconductor fabricating equipment, precision machines, measurement/inspection instruments, medical instruments, micromachines, and so on. The linear motion guide unit of the present invention is especially intended to more prolong scheduled intervals of substantial maintenance-free operation for lubrication to conduct better lubrication around the rolling elements to ensure smooth circulation of the rolling elements through the looped or closed circuit. 
         [0039]    A preferred embodiment of the linear motion guide unit constructed according to the present invention will be described in detail by reference to the drawings. The linear motion guide unit of the present invention has an elongated guide rail  1  having a pair of raceway surfaces  11  extending on each longitudinal side  24  of the guide rail  1 , and a slider  2  which fits over or conforms to the guide rail  1  for movement relative to the guide rail  1  through more than one rolling element or roller  5 . The slider  2  is chiefly composed of a carriage  3  having a pair of second raceway surfaces  12  lying in opposition to the first raceway surfaces  11  of the guide rail  1  to define the load-carrying races  20  and return passages  10  lying in parallel with the second raceway surfaces  12  on the carriage  3 , end caps  4  each having turnaround passages  30  to connect the respective load-carrying races  20  with the respective return passages  10 , and end seals  15  attached on outward end surfaces  35  of the end caps  4 , one to each end cap, and provided with lips  16  to close clearances left between the guide rail  1  and the slider  2 . More than one roller  5  and separator  19  interposed between adjacent rollers  5  are allowed to roll through circulating circuits  50  each of which is made up of the respective load-carrying races  20 , respective turnaround passages  30  and the respective return passages  10 . The linear motion guide unit of the present invention is preferably applied to the large unit having the guide rail  1  of, for example 55 mm in width. The slider  2  is made in a flanged type composed of upper middle portion and bulges extending sidewise from the upper middle portion. 
         [0040]    With the linear motion guide unit constructed as stated earlier, the rollers  5  running through one of the paired circulating circuits  49 , as shown in  FIGS. 2 and 3 , are allowed to transfer from the downside race  20  carrying downward load because of the slider  2  into the upside return passage  10  in the carriage  3  in a circulating manner. In contrast, the rollers  5  rolling through the other of the paired circulating circuits  49  are allowed to transfer from the upside race  38  carrying upward load because of the slider  2  into the downside return passage  10  in the carriage  3  in a circulating manner. Moreover, as the respective rollers  5  are right circular cylinders, the rollers  5  together with the separators  19  are born on either one of axially opposite ends thereof in sliding-contact relation against a retainer plate  13  extending across the carriage  3  and the end caps  4 , while come into rolling-contact around their circular outside surfaces with the races  20 . The retainer plate  13  is attached to the slider  2  by means of a retaining band  28  held to the end caps  4  at lengthwise opposite ends thereof. One of the paired circulating circuits  50 , as shown in  FIG. 3 , is made up of one of the paired load-carrying races  20 , the associated return passage  10 , and a shorter one of the turnaround passages  30  and a longer one of the turnaround passages  30 . In contrast, the other of the paired circulating circuits  50  is constructed as same as the one stated earlier. The paired circulating circuits  50  are intersected with one another in a way staggered from each other in lengthwise direction. The separators  19  as shown in  FIG. 3  are each interposed between any two adjacent rollers  5  to keep the rollers against contact or collision with each other. With the linear motion guide unit of the present invention, moreover, an inside seal  27  is placed in the concavity formed in the carriage  3  opposed to the top surface of the guide rail  1 . The inside seal  27  is held at the opposite ends thereof which fit into slits  44  made in the end caps  4 . 
         [0041]    With the linear motion guide unit constructed as stated earlier, a lower seal  14  is disposed to extend over the underneath of the carriage  3  and the forward and aft end caps  4 . The end seal  15  on an end surface  39  thereof makes engagement with an edge  52  around the end cap  4  to cover entirely a lubricant reservoir plate  21 . The slider  2  is assembled by the steps of laying the end cap  4 , the lubricant reservoir plate  21  and the end seal  15  one after another on the end surface  35  of the carriage  3 , then extending fastening bolts  55  through holes  45  in the end seal  15 , cuts  42  in the lubricant reservoir plate  21  and holes  46  in the end cap  4 , and driving the fastening bolts  55  into threaded holes, not shown, in the carriage  3 . A grease nipple, not shown, is driven into a threaded opening  49  in a lubricant resupply port  54  to supply lubricant into the circulating circuits  50  through the threaded hole  49  and the lubricant resupply port  54 . More especially, the grease nipple is driven into the threaded hole  49  after extended through a bolt hole  51  in the end seal  15  and a U-shaped cut  43  in the lubricant reservoir plate  21 . The guide rail  1  is made with some holes  17  that are used to fasten the guide rail  1  to any stationary bed. The carriage  3  of the slider  2  is made therein with some threaded holes  18  that are used to fasten the slider  2  to any component. On the end caps  4 , there are made with hooks below the underneath of the end cap  4  to hold in place the lower seal  14 , and also bolt holes  46  at four corners of the end caps  4  to allow bolts  55  to fasten the end caps  4  to the carriage  3 . The end cap  4 , as shown in  FIGS. 14 and 15 , is made at the middle area thereof with the lubricant resupply port  54  to introduce lubricant from the grease nipple, and further has the oiling grooves  53  to connect the lubricant resupply port  54  to the turnaround passage  30 . 
         [0042]    The return passage  10  is constituted with a circular hole defined inside a sleeve  6  that fits into a fore-and-aft bore  9  made in the carriage  3  of the slider  2 . The sleeve  6  is made of sintered resinous tubular member having cellular or porous structure, whether monolithic or split at  41  into two halves. The sleeve  6 , although fitting loosely inside the fore-and-aft bore  9 , is held in accurate place by spigots  48  raised above the end caps  4  fastened to lengthwise opposite end surfaces  35  of the carriage  3 . The end cap  4  is comprised of a spacer part  8  to define an inside curved half-surface of the turnaround passage  30  and an end cap major body  7  to define an outside curved half-surface  38  of the turnaround passage  30 . The end cap major body  7  is recessed below a rear surface of the end cap  4  to accommodate therein an assembly of the spacer part  8  to define the longer turnaround passage  30  and another spacer part  8  nested in the spacer part  8  to define the shorter turnaround passage  30  that gets intersected at right angles with the longer turnaround passage  30  and further staggered from the longer turnaround passage  30  in lengthwise direction of the slider  2 . More especially, the turnaround passage  30  in the end cap  4  are entirely formed by the combination of the end cap major body  7  to shape the outside curved half-surface  38  of the turnaround passages  30  with the spacer part to shape the inside curved half-surface  52  of the turnaround passage  30 . With the linear motion guide unit of the present invention, the slider  2  has a pair of sidewise opposing bulges in which there is provided the pair of circulating circuits  50  each of which is made up of the load-carrying race  20 , the return passage  10 , the longer turnaround passage  30  defined with the end cap major body  7  and the spacer part  8 , and the shorter turnaround passage  30  defined between the spacer parts  8 . The end cap  4  is kept in place relative to the carriage  3  and fastened to the carriage  3 , with using threaded bolts  55  which are extended through holes  46  in the end cap  4  and tightened into the carriage  3 . Upon precise location and connection of the end cap  4  to the carriage  3 , abutment of the sleeve  6  against a spigot  48  of the end cap  4  keeps accurate location of the end cap  4  relative to the sleeve  6 , making sure of precise alignment of the spigot  48  of the end cap  4  with the return passage  10  in the carriage  3 . Thus, end-to-end abutment between the sleeve  6  and the spigot  48  of the end caps  4  comes into flush connection of the return passage  10  with the turnaround passage  30  to finish the circulating circuit  49  of rectangle in transverse section with causing no discontinuity or gap at the connection between them. Coplanar continuity with no gap between the turnaround passage  30  in the end cap  4  and the return passage  10  defined by the sleeve  6  inside fore-and-aft bore  9  in the carriage  3  helps the rollers  5  transfer smoothly from the turnaround passage  30  to the associated return passage  10  and also from the return passage  10  to the turnaround passage  30  in a circulating manner. 
         [0043]    The lubricant reservoir plate  21 , especially as shown in  FIG. 4 , is backed up with the end surface  39  of the end seal  15  between the end cap  4  and the end seal  15  to fit in the recess  31  on the end cap major body  7 . More especially, the lubricant reservoir plate  21  is composed of a lubricant reservoir main body  22  which fits in a recess  31  formed in the end cap  4 , and an applicator nose  23  which fits in an opening  29  made in the lubricant reservoir main body  22  and extends into a through-hole  33  to communicate with the slot  32  in the turnaround passage  30 . The lubricant reservoir main body  22  is to store lubricant therein. With linear motion guide unit of the present invention, moreover, the applicator nose  23  is disposed to make engagement with the rolling elements to apply directly lubricant around the rolling elements while they roll through the turnaround passage  30 . The applicator nose  23  is composed of a basal part  26  and a nose part  25  raised above the basal part  26  to form a circular flat area  36  lying around the nose part  25 . Thus, after the lubricant reservoir plate  21  has fit into the recess  31  in the end cap  4 , the circular flat area  36  around the nose part  25  comes into abutment against a wall surface  37  of the recess  31  to keep in place the lubricant reservoir plate  21  and restrain the nose part  25  from protrusion into the turnaround passage. 
         [0000]    More especially, the through-hole  33  made in the outside circular surface  38  of the turnaround passage  30  in the end cap  4  has an elliptic figure elongated in a moving direction of the rollers  5 . The nose part  25  of the applicator nose  23  is made in a solid extending from the flat area  36  to a tip face  34  to fit into the elliptic opening. Thus, the flat area  36  of the basal part  26  has the elliptic figure to circumferentially fit into the through-hole  33  in the end cap. 
         [0044]    The applicator nose  23 , as molded to be higher in density, is capable of regulating the amount of resupplied lubricant to the necessitated minimum. The lubricant reservoir main body  22 , as especially shown  FIG. 5 , has an inverted U-shape including a main part  40  and bulges  41  extending from the opposite ends of the main part  40 . The lubricant reservoir main body  22  at the widthwise center thereof is cut out as shown at  43  in alignment with the lubricant resupply port  54  of the end cap major part  7  and at widthwise opposite ends thereof is cut away at  42  to allow the fastening bolt  55  to extend across the lubricant reservoir main body  22 . Moreover, the bulges  41  at the side edges thereof are cut away to make other hollows  42  which also allow the fastening bolt  55  to extend across the lubricant reservoir main body  22 . The applicator nose  23  is constituted with the basal part  26  and the nose part  25 . More especially, the basal part  26  has the flat area  36  which is larger in transverse section than the through-hole  33  in the end cap  4  to come into the end cap  4  around the through-hole  33 , thereby keeping in place the applicator nose  23  relative to the end cap  4 . The nose part  25  is integral with the basal part  26  and exposed at an end face  34  thereof to the slot  32  in the turnaround passage  30 . The porous compact of the lubricant reservoir main body  22  has a molded density less in the porous compact of the applicator nose  23 . With the linear motion guide unit constructed as stated earlier, thus, as the lubricant soaked in the applicator nose  23  is consumed, the lubricant previously held in the lubricant reservoir main body  22  may move to be resupplied into the applicator nose  23  with the capillary action. 
         [0045]    The porous compact to provide the lubricant reservoir plate  21  is made of finely powdery ultrahigh molecular weight synthetic resin, which is first subjected to compacting and the resulting compact is subsequently sintered at elevated temperature. In the sintered compact, the fine particles of the powdery synthetic resin partially coalesce with each other with leaving intercommunicating voids to provide open-porous or open-cellular texture whose pores or cells preserved among fine particles are open each other through interstices or channels. The sintered resinous material of the lubricant reservoir main body  22  has a molded density less than 0.60 g/cm 3 ˜0.70 g/cm 3  and the sintered resinous material of the applicator nose has a molded density in the range of from 0.60 g/cm 3  to 0.70 g/cm 3 . Thus, as the porous compact of the lubricant reservoir main body  22  is made less in retention of lubricant than the porous compact of the applicator nose  23 , lubricant is easy to move from the lubricant reservoir main body  22  to the applicator nose  23  and no phenomenon would occur that the lubricant reservoir main body  22  soaks up lubricant from the applicator nose  23 . As an alternative, the porous compact to provide the lubricant reservoir plate  21  may be made of, instead of the sintered resinous material as stated earlier, material for a wiper seal, which is disclosed in Japanese Laid-Open Patent Application No. 2009-144 746 which is a commonly-assigned senior application. The lubricant reservoir plate  21  may be made of polyester polyurethane foam of three-dimensional skeleton texture which is molded while compressed to ¼˜ 1/20 under compression to provide open-porous or open-cellular texture. The nose part  25  of the applicator nose  25  has a higher density than in the lubricant reservoir plate  21 , because of restricted or kept less partially or entirely in number and size of open-pores or open cells of the porous compact. That is, the nose part  25  of the applicator nose  25 , while extending to the end face  34  to be exposed in part to the turnaround passage  30 , is made entirely or at least in part higher in density than in the lubricant reservoir main body  22 . More especially, less the molded density in the porous compact is, the greater the pore size and pore number in the porous compact are. As a result, the amount of lubricant absorbed and preserved in the porous compact, or impregnation rate, would become higher. Generally, the porous compact under static or rest condition is in a state of retaining or preserving lubricant inside the open pores or cells. Once the porous compact comes into contact or engagement over the outward surface or skin thereof with the rolling elements such as the rollers  5  to experience any external force, the lubricant seeps out of the porous compact with using capillary action to apply the lubricant, for example, around the rolling elements  5 . Thus, as the pore size and/or the number of pores in the porous compact increase, the lubricant squeezed out of the porous compact is more in quantity than in the porous compact high in molded density. With the porous compact having high molded density, moreover, there is a greater likelihood that the volume of continuous pores or cells, or the open-pore size and the number of open pores inside the porous compact decreases and, therefore, the amount of lubricant absorbed and preserved in the porous compact, or the impregnation rate, declines with the result of less amount of lubricant oozing out of the porous compact with capillary action, causing tougher application of lubricant around the rolling elements. 
         [0046]    Referring to  FIGS. 18 and 19 , there is shown another version of the linear motion guide unit of the present invention. A lubricant reservoir main body  22  in the lubricant reservoir plate  21  has a bottomless hole  29 A to fit over an applicator nose  23 A. With the applicator nose  23 A, a nose part  25 A is integral with a basal part  26 A having the circular flat area  36 . The applicator nose  23 A is the same in function as the applicator nose  23  previously described, so that the previous description will be applicable. In  FIG. 20 , moreover, there is shown a further another version of the lubricant reservoir plate  21 . With the lubricant reservoir plate  21  in this version, the lubricant reservoir plate  21  has a stepwise hole  29 B to fit over an applicator nose  23 B, which has a nose part  25 B and a basal part  26 B having the circular flat area  36 . The applicator nose  23 B is kept in place relative to the end cap major part  7  after the circular flat area  36  of the basal part  26 B has snugly fit in the stepwise hole  29 B. The applicator nose  23 B is the same in function as the applicator nose  23  previously described, so that the previous description will be applicable. With the linear motion guide unit of the present invention, the porous compact to provide the lubricant reservoir plate  21 , instead of the sintered resinous resins and the polyester polyurethane foam recited earlier, may be made of fibrous material such as nonwoven cloth, felt, cotton.