the invention of this application relates to a spindle mounted rotary member including an engagement mechanism . the example brake assembly shown includes a braking mechanism 50 located between a spindle 20 and a tire 100 . the spindle 20 serves to rotatively mount the tire 100 and contained braking mechanism 50 to an associated part . an example of this associated part would be the vehicle frame of a scissorlift . the particular embodiment would be bolted onto such frame ( shown in dotted lines 200 in fig1 ) from the backside by bolts 201 . this would tightly retain the mounting plate 21 of the spindle to the frame 200 against the weight and dynamic loading to and from the vehicle or device ( such as a scissorlift ) and the tire 100 . note that the particular mechanism 10 disclosed is spring applied and pressure released braking mechanism . therefore , a hole 202 would be provided in the frame in order to allow a suitable selective pressurization hydraulic line 205 to be interconnected to the brake assembly 10 . ( this hole 202 also aids in localizing and weight transfer between the spindle and the frame 200 due to flange 23 engaging the sides of the hole 202 .) in addition to the mounting plate 21 , the spindle 20 has an enlarged primary bearing area 30 , a relatively reduced secondary bearing area 40 and a reduced oil passage extension 45 . the enlarged main bearing section 30 serves to carry the primary weight of the vehicle by forming the primary interconnection for the main bearing 31 and the primary torque by the attachment of the reaction disks 33 thereto . it is preferred that the main weight loading of the wheel be through this ball bearing ( being of large size and of proximity to the enlarged diameter plate 21 and frame , it can dissipate heat more efficiently ). in addition , the preferred main bearing 31 as shown is a ball bearing located between the spindle mounting plate 21 and two separate snap rings 35 . one snap ring is internal to the spindle 20 and the other is external to plate 63 . plate 63 has a small inner lip 65 adjacent to the outer inside edge of bearing 31 . this allows the bearing at this location to take the forces inwardly and outwardly between the wheel 100 to the frame 200 ( i . e ., separate thrust bearings are not necessary ). the secondary bearing area 40 aids in the support of the weight loading of the wheel . incorporating a needle bearing 41 at this location also allows room and physical placement for the parts of the braking mechanism 50 radially outward therefrom . this lowers the necessary diameter of the housing 60 in respect to alternative bearings . it also allows the bearing outward of most of the braking mechanism 50 , thus aiding in reducing wobble and in localizing the later described dynamic seal 46 . located off the end of the secondary bearing area 40 is a reduced oil passage extension 45 . this reduced oil passage section is surrounded by the main dynamic seal 46 for the actuation mechanism . by being reduced in diameter , this has the effect of reducing the axial thrust of the “ piston area ” between the braking mechanism 50 and the spindle 20 during pressurization from line 205 ( compare the area of the reduced oil passage extension 45 which would be necessary if a dynamic high pressure seal was located about the larger diameter 30 of the spindle with that of the main bearing 30 , for example ). this reduces any axial shifting of the wheel 100 in respect to the spindle 20 upon the pressurization of the brake assembly 50 . this lengthens the service life of the package . this dynamic seal 46 is also the only high pressure seal in the entire device which will routinely be subject to rotary movement between adjoining parts ( all of the other parts of the brake assembly 10 are either located between two relatively immovable parts — the unitary housing 60 for example — or are located between a part which will be subject to rotative forces only during engagement and disengagement — the piston 57 for example . this design minimizes the necessity of complex manufacturing processes on adjoining parts ( for example grinding ) while also lowering the cost of parts ( larger diameters of seals are of significant cost ). the brake mechanism 50 sits surrounding the spindle so as to mechanically rotatively interconnect the tire 100 to the spindle 20 as well as providing for a compact engagement mechanism . the particular braking mechanism 50 includes a reaction support member 51 , a housing 60 , and a spinner nut locking member 80 . the reaction support member 51 serves to interconnect the housing 60 with the outer needle bearing 41 thus to pass any radial forces therebetween . in addition the reaction support member 51 has an oil passage 52 which extends from the reduced oil passage extension 45 to the main activation cavity 54 adjacent piston 57 . as the activation cavity 54 is located between first and second piston seals 55 , 56 the pressurization of the passage 26 in the spindle will cause movement of the piston 57 against the force of the disk spring 59 so as to deactivate the braking engagement mechanism . upon the cessation of pressurization of the passage in the spindle , the piston 57 will move the other way due to the force of the disk spring 59 , this in turn will engage the braking plates 58 which are connected to the housing 60 with reaction plates 33 which are interconnected to the spindle 20 , thus to apply a braking action for the device . note that the areas of piston seals 55 , 56 are the only location where significant axial movement of two adjoining parts is maintained . as the swept area in the preferred device has both locations on the outer circumferential of a single part , manufacturing can occur at a single grinding location . this reduces the cost of the device . ( since the piston seals 55 , 56 are reset into grooves in the piston 57 , the piston can be turned .) note also that it is possible to assemble the piston 57 and reaction support member 51 together for later incorporation as an integral unit into the remainder of the device 10 . this allows the premanufacture of this unit in one location ( preferably along with seal 46 ) with integration to the remainder of the device occurring in another less precise location ; all important seals 65 , 66 ( and 46 ) are physically protected . the locations can be very remote or even across the country from each other . this is aided by the fact that except for these parts the other dimension that should be held is the outer surface of the reduced oil passage section 45 of the spindle 20 . the spinner nut locking member 80 serves a dual purpose of assisting in the weight loading from the wheel 100 and the housing 60 to the exterior surface of the reaction support member 51 ( which then passes along to the spindle 20 through bearing 41 ). the spinner member 80 thus functions as an integral weight transfer process . the spinner member 80 in addition also axially pressure preloads the inner edge of the disk spring 59 . this provides the engagement forces for the braking mechanism 50 . note that it is preferred that the spinner nut 80 in contact with the adjacent shoulder 53 of the reaction member 51 to provide for a reliable braking force across individual units within any series of devices 10 . note that it is preferred to assemble the entire device before adding the spinner nut . assembly can thus occur with hand tools without regard for the loading of the spring 59 . the spinner nut can then be included with a spanner wrench . ( the screw threads outside the nut would provide the leverage to compress the spring 59 .) the housing 60 serves to contain the spindle 20 and braking mechanism 50 in addition to providing an integral weight transferring hub for the tire 100 . in respect to containing the braking mechanism 50 , the wheel 100 is substantially the same inner and outer diameter and width as it would be without such mechanism . this allows a given manufacturer to produce both braked and unbraked designs with a single frame . this would include other parts associated with the frame as the main addition to unbraked units is the addition of pressure line 205 . in respect to the transfer of weight , the housing 60 shown is primarily made of two cylindrical plates 62 , 63 and a surrounding hub 64 . in the embodiment shown , all of these pieces are integrally interconnected together via a series of hex screw bolts 70 that extend circumferentially about the device from both ends . the inner cylindrical plate 63 of the housing is interconnected to the spindle 20 directly through the main bearing 31 . the fact that all pieces are radially aligned facilitates the weight transfer between the parts , enabling them to function as a single unitary piece . due to this bearing and the existence of snap rings 35 ( one internal , one external ), this cylindrical plate 63 of the housing is not able to shift axially of the device . as the other housing parts 62 , 64 are integrally connected to this plate 63 , the plate 63 thus serves as the primary retention mechanism between the spindle and the remainder of the brake assembly 50 . the outer cylindrical piece 63 passes its forces through the spinner nut locking member 80 which is itself securely interconnected through the reaction support member 51 to the inner bearing 41 . this allows forces on the outer end of the assembly to pass through the needle bearing 41 into the secondary bearing area 40 of the fixed spindle 20 . the tire 100 completes the assembly 10 . this tire 100 is directly interconnected to the housing 60 so that this housing serves as a hub for the tire . this allows the assembly 10 to have a smaller diameter and less complicated construction than with the alternative of a separate wheel hub . note that the load of the tire 100 surrounds the two bearings 31 , 41 . the radial transfer of forces between the two is thus readily accomplished . further , since virtually all of the brake mechanism 50 rotates at the same time and at the same speed of the tire 100 there is no need for complicated fluid passages or seals : the dynamic seal 46 provides for substantially all of the rotational movement between adjoining parts in the device . the remaining seals are static seals ( mostly relative to the housing 60 , reaction support member 51 ), or subject to small movements under limited condition ( the piston seals 55 , 56 during a transition between the two operating states of the brake — on or off ). the particular preferred embodiment has a tire 100 substantially 12 ″ in diameter and 4 . 3 ″ in width . the total unit is 5 ″ wide including spindle plate 21 . the tire has a depth of 1 + ¾ ″ to the outer diameter of the housing 60 . the support piston 57 has a hydraulic cavity 54 with an outer diameter of 5 + ⅜ ″ and an inner diameter of 3 + ⅛ ″. the reduced oil passage extension 45 of the piston has a diameter of 0 . 5 ″. the disk spring 59 is 6 ″ in diameter with an initial depth of 0 . 38 ″. it develops substantially 500000 pounds of force at 0 . 09 ″ deflection . the preferred embodiment of the invention discloses a method of manufacture including preassembly of the reaction member and piston , the loading of the spring by the spindle nut , the multi - piece housing , and the modifications of the spindle mounting plate to accomplish differing frames . the use of a novel seals ( only three seals between moveable parts ) and the reduced sized oil passage extension simplify and lengthen the service life of the assembly . the availability of room about the outer end of the spindle for the brake and the use of the intermediate reaction support member shorten the unit to substantially the width of the surrounding tire . the oil passage is simple through the spindle , with a double back path to the brake piston cavity . the total unit can be used without the brake package without structural modification . a single ball bearing serves as a main bearing as well as the thrust bearings . it is further possible to remanufacture the device from one end . note that due to the simplicity of the structure of the brake assembly , alternate applications can be readily handled by a single design . for example , the spindle mounting plate 20 serves to integrate the brake assembly 10 with its associated device . it is a fairly easy matter to design and make differing spindle mounting plate 21 to provide for a wide number of differing applications with a basic single device . further , maintenance of the device is facilitated : by removing the spinner nut locking member 80 and the outer hex screw bolts 70 it is possible to entirely disassemble the braking mechanism to replace any pressure components or disk components therein without significant compromise to the overall structural strength of the device once reassembled . additional example , the moving parts of the brake ( disks 33 , 58 ; piston 57 ; disk spring 59 ; and , seal 46 ) can be entirely omitted without structural compromise to the tire / spindle weight supportive rotary interconnection . therefore , although the invention has been described in its preferred form with a certain degree of particularity , it is to be understood that modifications can also be made without deviating from the invention as hereinafter claimed .