as required , detailed embodiments of the present invention are disclosed herein ; however , it is to be understood that the disclosed embodiments are merely exemplary of the invention , which may be embodied in various forms . therefore , specific structural and functional details disclosed herein are not to be interpreted as limiting , but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed structure . the reference numeral 1 generally designates an adjustable chair arm assembly which embodies the present invention . the assembly 1 generally includes a stationary chair arm subassembly or support unit 2 and a movable chair arm subassembly or armrest housing unit 3 having an armrest pad unit 4 pivotally connected thereto . the housing unit 3 is movable relative to the support unit 2 to enable vertical adjustment of the pad unit 4 relative to a chair seat member 5 of a chair 6 , the pad unit 4 is pivotally adjustable about a substantially vertical pivot axis 7 . the chair 6 may be an executive type office chair or a chair of the type known as task seating , and the seat member 5 may be adjustable for height and tilt ( not detailed ). the support unit 2 includes a generally l - shaped support member 10 formed by a substantially horizontal leg 11 and an upright or vertical leg 12 extending upwardly from the horizontal leg 11 . the angle between the horizontal and vertical legs 11 and 12 may be slightly obtuse to give the upright leg a somewhat diverging orientation relative to the seat member 5 . on the illustrated support member 10 , the horizontal and vertical legs 11 and 12 are connected by a curved bend 13 . the support member 10 is a of a flattened shape and is preferably formed of a metal , such as steel or an aluminum alloy . the horizontal leg 11 of the support member 10 has bores 14 ( fig1 and 4 ) to receive fasteners such as screws ( not shown ) to attach the support member 10 to the underside of a base member 15 of the chair seat member 5 . an upper end 17 of the upright leg 12 has elongated , vertical rectangular cutouts 18 ( fig2 ) formed on opposite edges thereof . each cutout 18 has an upper shoulder 19 , a lower shoulder 20 , and an inner edge 21 . the cutouts 18 are preferably identical . the housing unit 3 includes an armrest housing 24 formed by a hollow , lower stem portion 25 which diverges into an upper platform portion 26 . the stem portion 25 has a support member receiving passage 27 ( fig2 and 3 ) formed therethrough , and the platform portion 26 is closed by a platform plate 28 . the platform plate 28 is connected to the platform portion 26 by fasteners such as screws 29 which are received in screw bosses 30 within the platform portion 26 of the housing 24 . the stem portion 25 has vertical ribs 32 ( fig2 and 3 ) extending into the passage 27 which stiffen the wall of the stem portion 25 and form slide bearings for sliding engagement with the upright leg 12 of the support member 10 . additionally , the ribs 32 maintain the position of the upright leg 12 within the passage 27 . the housing 24 is preferably formed of a durable molded plastic which may be colored to match or coordinate with upholstery ( not shown ) on the seat member 5 and other components of the chair 6 . the pad unit 4 includes an armrest pad member 35 having an armrest pad mounting plate 36 positioned within a lower recess 37 of the pad member 35 . the illustrated pad member 35 is formed by a durable plastic outer layer or skin 38 having a padding material 39 , such as a foam resin , positioned therein , as by injection in a liquid state . the mounting plate 36 is connected to the pad member 35 by fasteners such as screws 41 extending into screw bosses 42 formed by the skin 38 within the recess 37 . the bosses 42 may include some kind of nut member ( not shown ) embedded therein to positively receive the screws 41 . the pad member 35 is pivotally connected to the housing 24 by a pivot bolt 45 extending between the platform plate 28 and the mounting plate 36 and a nut 46 . a head of the bolt 45 is positioned in a bolthead recess 47 formed in the underside of the platform plate 28 , and the nut 46 is positioned in a nut recess 48 formed in the upper side of the mounting plate 36 . the bolt 45 is located along and forms the vertical pivot axis 7 . the assembly 1 includes a pivot retainer mechanism 52 engaged between the pad unit 4 and the housing 24 to releasably retain the pad member 4 in the desired pivotal position relative to the housing 24 . in the preferred embodiment of the present invention , the pivot retainer mechanism 52 is a spring ball detent mechanism including a plurality of detent impressions 54 ( fig4 ) formed in the upper surface of the platform plate 28 in circumferentially spaced relation about the pivot axis 7 and the bolt 45 . the detent impressions 54 are formed in diametrically opposed pairs across the bolt 45 . the detent mechanism 52 includes a pair of detent balls 56 which are resiliently urged by detent springs 57 ( fig2 ) toward the platform plate 28 . the detent springs 57 are located in detent spring recesses 58 in the underside of the mounting plate 36 . the detent mechanism 52 allows the armrest pad 35 to be snapped into a plurality of positions about the bolt 45 relative to the housing 24 . the assembly 1 includes a slide retainer mechanism 62 engaged between the housing 24 and the upright leg 12 of the support member 10 to releasably retain the housing unit 3 in a desired vertical position relative to the support member 10 . in the preferred embodiment of the assembly 1 , the slide retainer mechanism 62 includes a ratchet member 63 and a pawl member 64 . the ratchet member 63 is positioned in one of the cutouts 18 formed in the upper end of the upright leg 12 . the illustrated ratchet member 63 is an elongated rod having external helical threads 66 formed on an external surface thereof . the ratchet member 63 has a length which allows it to fit loosely between the upper and lower shoulders 19 and 20 of the cutout 18 . the ratchet member 63 is retained within the cutout 18 by a ratchet channel 67 ( fig3 ) formed by a pair of the ribs 32 extending inwardly from the wall of the stem portion 25 . the pawl member 64 is positioned within a pawl recess 70 formed in the stem portion 25 of the housing 24 . the illustrated pawl member 64 has internal threads 72 formed on an end surface thereof which cooperate with the external threads 66 of the ratchet member 63 . the end surface of the pawl member 64 is preferably cylindrically concave to conform to the external contour of the ratchet member 63 . the pawl member 64 is pivotally connected to the lower end of a pawl release lever or control lever 74 by a pawl pivot pin 75 . the pawl control lever 74 is pivotally connected to the housing 24 by a lever pivot pin 76 within a lever slot 77 formed on one side of the housing 24 . a pawl spring 79 is engaged between the housing 24 and the lever 74 and resiliently urges the upper end of the lever 74 outward which urges the lower end of the lever 74 and the pawl member 64 inward into engagement with the ratchet member 63 . the pivot pins 75 and 76 may be rolled spring pins . the assembly 1 includes an upper stop pin 82 and a lower stop pin 83 ( fig2 ) which limit upward and downward movement of the housing 24 relative to the support member 10 . the stop pins 82 and 83 extend between the walls of the stem portion 25 of the housing 24 through the cutout 18 on the opposite side from the ratchet member 63 . engagement of the upper stop pin 82 with the upper shoulder 19 limits upward movement of the housing 24 , while engagement of the lower stop pin 83 with the lower shoulder 20 limits downward movement of the housing 24 relative to the upper leg 12 . the ratchet member 63 fits either of the cutouts 18 whereby the housing unit 3 can be interchangeably assembled on a support member 10 one either the right side or the left side of the seat member 5 of the chair 6 . the adjustable chair assembly 1 of the present invention provides a wide range of vertical and pivotal adjustment of the position of the armrest pad unit 4 to support the forearms of an occupant of the chair 6 . the armrest pad units 4 can be adjusted in such a manner as to support the forearms of a typist seated in the chair 6 in relation to a typing keyboard ( not shown ) to prevent repetitive motion injuries , such as carpal tunnel syndrome . the assembly 1 can also be easily and conveniently adjusted to the comfort requirements of virtually any occupant of the chair 6 . it is to be understood that while certain forms of the present invention have been illustrated and described herein , it is not to be limited to the specific forms or arrangement of parts described and shown .
a vertically adjustable chair arm with a rotatable armrest includes an armrest support member extending upwardly from a chair seat and an armrest housing telescoped onto the support member . an armrest pad member is pivotally connected to a top end of the housing . a manually operated ratchet mechanism is engaged between the housing and the support member to releasably retain the housing in a selected vertical position on the support member . a spring ball detent mechanism is engaged between the armrest pad member and the housing and releasably retains the pad member in a selected pivotal position relative to the housing .