a hospital bed 10 having a full length rail 12 as shown in fig1 - 2 or a rail 12 &# 39 ; of shorter length , as shown in fig6 is provided . primed numerals are used herein to refer to parts shown in fig6 a and 7b which are similar , but not necessarily identical to the corresponding enumerated parts in the embodiment of the invention shown in fig1 - 5 and 8 - 9 . the same numerals are used for both embodiments where substantially identical parts are employed . in either case , the rail is adjustable both vertically and horizontally to allow it to protect a patient or be stored under the bed when not in use . the bed 10 ( 10 &# 39 ; in fig6 ) includes a base 14 ( 14 &# 39 ; in fig6 ) supported by four wheels 16 . an angle iron frame assembly 20 ( 20 &# 39 ; in fig6 and 7 ) is supported by the base 16 . the frame assembly 20 supports an articulatable frame 18 including back , seat , thigh and foot portions 22 , 24 , 26 , 27 . each portion may include a wire grid supported by a plurality of coil springs ( not shown ). movement of these portions may be accomplished manually by means of cranks or by employing one or more electric motors . both approaches are well known to the art and require no further discussion herein . a mattress 28 is supported by the grid . a head panel 30 and a foot panel 32 are mounted to opposing ends of the frame assembly 20 . referring to fig3 - 5 and 7a - 7b , a rail assembly 34 ( 34 &# 39 ; in fig7 a - 7b ) is shown for supporting the side rails 12 ( 12 &# 39 ;) and allowing them to be moved to a desired position . each rail 12 includes a u - shaped housing 36 ( 36 &# 39 ;) secured to the bottom portion thereof , a connecting link 38 ( 38 &# 39 ;) positioned within the housing , and a latch 40 ( fig7 a ) positioned near one end of the connecting link . a latch spring 42 is provided for urging the latch 40 into engagement with a shoulder 38a ( fig7 a ) defining the end of the link . a pair of pivot arms 44 are secured to each rail housing 36 ( 36 &# 39 ;) by means of a pair of pivot pins 46 , a pair of button screws 48 , and a plurality of washers 50 as shown in fig7 a . the connecting link includes two notches 52 therein to accomodate the respective pivot pins . steel rivets 53 secure the housing 36 &# 39 ; to the rail 12 &# 39 ;. in order to prevent the rail 12 from dropping rapidly upon release of the latch 40 , a braking mechanism as shown in fig4 - 5 is incorporated within the rail housing . the braking mechanism includes a cam link 54 , a retractor spring 56 , and a cable 58 having one end secured to the retractor spring and an opposite end secured to the rail housing 36 . the cam link 54 is riveted to the connecting link 38 at one end and secured to a pivot pin 46 at its other end . a second cam link ( not shown ) connects the opposite end of the connecting link with the second pivot pin . the cam link , cable and spring are arranged such that the spring increases in length as the pivot arms 44 ( and cam link ) rotate to move the rail 12 downwardly , thereby tending to resist the downward movement thereof . upon raising the rail , the spring length shortens and works to offset the gravitational forces urging the rail downwardly . fig4 shows the positions of the pivot arm connecting link and cam link when the rail is in a lowered position . the axis ( i . e . the rivet 60 connecting the cam link to the connecting link ) about which the cable extends is positioned relatively far from the bolt 62 which secures the retractor spring 56 to the rail housing . the spring is accordingly extended as the cable is not elastic . in contrast , fig5 shows the rail in the operating position . the axis about which the cable is wrapped ( i . e . the pivot pin 46 ) is closer to bolt 62 which allows the spring 56 to contract . when the pivot pin 46 shown in fig5 is positioned outside of the notch 52 in the connecting link , the second pivot pin , not shown in the figure , is positioned within the second notch ( also not shown in this figure ) within the connecting link . the notches assure that the pivot arms and cam links will be locked in the proper positions when the rail is either raised or stored . the cam links should be maintained in a non - horizontal position to facilitate their rotation upon exertion of a horizontal force upon the unlatched rail 12 . a pair of parallel mounting shafts 64 are provided for mounting each rail 12 ( or 12 &# 39 ;) to the main frame assembly 20 ( or 20 &# 39 ;). one end of each shaft is pivotably secured to one of the pivot arms 44 . the opposite ends therof are bifurcated and each includes a roll pin 66 extending therefrom . slide tubes 68 are mounted to cross rails 70 ( 70 &# 39 ;) of the frame assembly 20 ( 20 &# 39 ;) for receiving the mounting shafts 64 . stop members 72 are secured to the cross rails 70 adjacent the inner ends of the slide tubes 68 . at least one of the stop members 72 associated with each rail 12 ( 12 &# 39 ;) includes an angular surface 72a facing the inner end of the slide tube 68 as best shown in fig7 b . the stop member together with the cross rail , further defines a channel 72b within which the mounting shaft 64 may be positioned , the channel having an elongate opening to prevent the roll pin 66 from interfering with the movement of the mounting shaft . the roll pin is oriented towards the channel opening when the rail is in the down position . the distance between the leading edge of the angular surface 72a and the slide tube 68 is approximately equal to the diameter of the roll pin . when the rail 12 is pulled out and then moved to the up position , thereby rotating the pivot arms 44 and mounting shafts 64 , the angular surface 72a urges the roll pin outwardly . the rail will accordingly be located in its outermost position when fully raised . the location of the pin between the stop member and slide tube assures that there will be virtually no lateral play associated with the rail when in use . a pair of retractor springs 74 are provided for resiliently urging each of the opposing rail assemblies 34 towards the center of the bed 10 . each spring 74 is secured to the bifurcated ends of an opposing pair of mounting shafts 64 . the portion of the roll pin extending between the bifurcated portions of each shaft serves as a spring affixation member . fig7 b illustrates the position of a mounting shaft and associated roll pin after the rail has been pulled by the retractor springs 74 to a storage position beneath the articulatable frame which supports the mattress . a second latch mechanism is provided for maintaining the rail 12 in the outermost lateral position with respect to the bed frame . fig3 a , 8 and 9 best illustrate this mechanism . the principles of operation of the mechanisms shown in fig1 - 2 , 8 - 9 and 6 , 7a - 7b are the same , the only structural differences being those to accomodate the different spacings of the pivot arms 44 , and therefor the mounting shafts 64 , used in conjunction with the different size rails 12 and 12 &# 39 ;. referring to fig1 - 3 and 8 - 9 , the mounting shafts 64 each include a peripheral groove 76 therein . a catch bar 78 having a pair of elongate holes 80 and a pair of keyholes 82 extends perpendicularly to the mounting shafts 64 , each of the shafts extending through one of the keyholes . the catch bar 78 is secured to a catch link 84 which is , in turn , secured to a cover plate 86 . the cover plate 86 includes a plurality of elongate openings 88 through which shoulder bolts 90 and a release latch 92 extend . the catch link is accordingly movable with respect to the cover plate although secured thereto by means of the shoulder bolts . a retractor spring 94 having one end secured to the catch link and the other end to the cover plate resiliently urges the catch link , and therefore the catch bar , in the latching direction . the cover plate , being bolted to the frame assembly 20 , is immobile . since the length of the catch bar 78 in the above figures is several feet , a pair of catch bar supports 96 are secured thereto to maintain it in a horizontal position . the catch bar supports are bolted to the main frame assembly 20 . a similar locking mechanism is shown in fig6 and 7a - 7b . the catch bars 78 &# 39 ; employed in the embodiment include elongate openings 80 &# 39 ; and keyholes 82 &# 39 ; in different relative locations for mounting them to the cover plates 86 &# 39 ;. since the catch bars are considerably shorter than those in the above - described embodiment of the invention , additional supports are not required . the second latch mechanism maintains the rail assembly 34 ( 34 &# 39 ;) in its outermost position regardless of the vertical position thereof unless the release latch is actuated . the smaller portions of the keyholes engage the grooved portions of the respective mounting shafts , thereby preventing the rail from being moved inwardly . if the latch is accidentally actuated when the rail is in the raised position , the stop members 72 act as a safety mechanism by maintaining the rail in the outer position . the release latch 92 is normally utilized after the rail 12 has been fully lowered . by exerting a horizontal force in the appropriate direction upon the release latch , the catch bar 78 ( 78 &# 39 ;) is moved such that the large portions of the keyholes 82 ( 82 &# 39 ;) are aligned with the mounting shafts 64 . this allows the retractor spring 74 to pull the mounting shafts and rail 12 connected thereto inwardly to the position shown in fig8 . when the rail is pulled out from under the bed , the catch bar 78 ( 78 &# 39 ;) automatically engages the grooved portion of the mounting shaft due to the force exerted on the catch link 84 ( 84 &# 39 ;) by the retractor spring 94 secured thereto .