Prony brake dynamometer pdf download

 

    brakes, transmit torque mechanically. ○ Mechanical brake: In mechanical brake friction force is applied by giving pressure on the surface of drum or disk. Prony Brake - Download as Powerpoint Presentation .ppt /.pptx), PDF File .pdf), Text File .txt) or view presentation slides online. prony. applying a brake, Hence dynamometer is a brake with a device of measuring the frictional resistance. The Prony Brake is a braking device based on pure mechanical friction. The kW Mechanical Loads can also operate as dynamometers to measure the.

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    Prony Brake Dynamometer Pdf Download

    Prony brake dynamometers at a tractor contest in Schematic of a Prony brake. The Prony Brake is a simple device invented by Gaspard de Prony in to measure the Create a book · Download as PDF · Printable version. PDF EBOOK here { inaferigox.cf }. . Types of dynamometers: 1) Absorption dynamometer: Prony brake dynamometer Rope Prony brake dynamometer Construction & Working: • A simplest form of an. PDF | This paper discuss comparative strudies of the tread brake dynamometer The brake dynamometers are widely used to evaluate the performance of brake Download full-text PDF He invented the Prony Brake Dynamometer.

    A stator shaft aligned with the rotating shaft is sealed within a cylindrical drum which is coupled to the rotating shaft and rotated thereby. A hydraulic system actuates a plurality of pistons in radially outward directions so as to frictionally engage the inner surface of the rotating drum. The resulting heat build-up is transferred through the finned, high-heat transfer lateral walls of the drum to water in a tank in which the rotating drum is located. Brake lubrication is provided by a closed lubricant circulation system within the rotating drum capable of providing efficient, uniform lubrication of the brake surfaces. The drum is sealed to prevent the loss of lubricant therefrom as well as water contamination therein while the level of lubricant in the brake cell is easily checked by visual means. The closed lubricant circulation system protects the friction material from wear and lubricant glazing and permits the brake to operate at high temperatures without lubricant loss due to "cook off". Means are provided for continuously filtering the brake lubricant for removing "slough off" friction material therefrom.

    This dust is very destructive to bearings and seals and its accumulation causes recirculation problems and a somewhat unstable loading characteristic. In any application save perhaps that of an automobile brake this type of nonlubricated friction engaging mechanism would have a usable lifetime of short duration.

    The accumulated residue of metal upon metal during the wearing process limits the lifetime of a conventional automobile brake to perhaps less than hours of continuous, high energy absorption, rotational engagement.

    USA - Prony brake dynamometer - Google Patents

    A dynamometer designed on the same limited operational basis as an automobile brake would be a design failure. A dynamometer application requires thousands of hours of accumulated operation before the occurrence of a major failure. Water is the most common means for absorbing the mechanical equivalent of the heat generated in the power absorption process.

    At the same time, water is the most common limiting factor in the dynamometer operating environment.

    Dynamometer: Introduction and Types

    The vast majority of installations of power testing equipment suffer from shortages in water availability or are provided with expensive water supply installations. The water impeller type of dynamometer requires a fixed amount of water usage which cannot be improved due to the formation of steam pockets on the receding edge of the impeller vanes. This negative pressure on the nonpressurized side of the impeller vane causes water to boil at a reduced temperature resulting in turbulence and a severe limitation on the impeller's capacity to provide a continuous, constant load or create torque resistance.

    In addition, the metallic impeller is subject to erosion in the form of sublimation due to the formation of these steam pockets on the impeller vanes.

    The Prony brake type of dynamometer is thus a much more economical and efficient load absorption device than its impeller counterpart. Another limitation in conventional dynamometer design involves the failure to take advantage of the full cooling capacity of water. The resulting 1, BTU's is available if the internal pressure of the evaporative device can be maintained at atmospheric pressure.

    Also operating in these conditions avoids excessive temperatures and the unsafe conditions associated therewith. Prior art dynamometers incorporating a lubrication system also suffer from various limitations. In these systems a certain amount of lubrication provides protection of the internal contacting members and continues to do so up to a point where the lubricant either breaks down into its organic components or volatizes "cooks off".

    The breaking down of the organic lubricant results in the formation of a glazed coating on the friction material and a reduction in the torque engaging capacity.

    A skipping action can occur with the introduction of the lubricant between two smooth surfaces such as a smooth glazed brake lining and a smooth metal brake drum.

    Without this glazing, or breakdown, the service life of the lubricated brake unit is virtually unlimited.

    In addition, current dynamometer lubrication systems are unable to provide uniform lubrication between brake drum units or along the entire length of a brake unit, fail to confine the lubricant in a closed environment which becomes an important factor when expensive lubricants are used at high temperatures, and apply the lubricant to the engaging surfaces in a nonflowing manner. The present invention does not suffer from these limitations in that it offers a Prony brake type of load absorption unit, or dynamometer with conventional measuring instrumentation coupled thereto, which has a circulating, closed lubrication system which not only substantially extends the usable lifetime of the components therein, but also allows the unit to achieve larger loading capacities without the need for increasing the unit's heat dissipation capacity.

    The brake assembly is enclosed in a sealed drum coupled to a rotating shaft and rotationally displaced thereby within a water-filled tank. Friction engaging surfaces positioned within the drum adjacent to its lateral surface are displaced radially outward by means of a plurality of opposed, hydraulically-actuated brake shoes symmetrically positioned about the axis of rotation. Frictional heat buildup is transferred via the thin, finned metallic lateral surface of the drum to the surrounding water reservoir, which may be either closed or circulating in nature.

    A closed lubrication system circulates a lubricant within the brake cell to provide a suitable coefficient of friction between the engaging surfaces at high operating temperatures without lubricant loss from the brake drum due to "cook off". By means of this improved, closed lubrication system and by completely submerging the brake assembly in the water-filled tank, excessively high water temperatures are avoided with system safety thus enhanced and water cooling requirements substantially reduced.

    In a preferred embodiment, a silicon lubricant is utilized within the brake drum and is continually circulated over the friction engaging surfaces for improved brake operation. Provision is also made for the continuous filtering of the lubricant for the removal of displaced friction material therefrom. In the circulating lubrication system the lubricant is temporarily "trapped" away from the heated surfaces and then allowed to flow into the internal parts of the brake unit.

    The lubricant is then displaced from the friction engaging surfaces where maximum heating occurs by the rotation of the drum for improved brake cooling and limiting the operating temperature of the lubricant. However, the invention itself, as well as further objects and advantages thereof will best be understood by reference to the following detailed description of a preferred embodiment taken in conjunction with the accompanying drawings, where like reference characters identify like elements throughout the various figures, in which: FIG.

    A prime mover not shown is coupled to a universal yoke 12 which includes a shaft portion Shaft portion 13 is keyed so as to engage an outer flange 15 which, in turn, rotates with universal yoke 12 in response to the action of the prime mover. Outer flange 15 is rigidly coupled to inner flange 16 by means of a shear bolt Inner flange 16 is, in turn, fixedly coupled to drive shaft 14 by means of recessed keying portions Thus, drive shaft 14 rotates in response to the rotation of universal yoke 12 by virtue of the shaft coupling provided by linked outer and inner flanges 15, 16 and their respective shaft keying elements.

    Shear bolt 17 provides for the rapid disconnection of the drive shaft 14 from the universal yoke 12 in the event of an abnormal operating condition such as in the application of excessive torque values by the prime mover upon drive shaft Fixedly coupled to drive shaft 14 by means of keying elements 18 inserted in the drive shaft are outer and inner spacers 22, Positioned between spacers 22, 24 is a sprocket wheel 20 having a plurality of teeth around its periphery which are engaged by a flexible link chain Drive sprocket 20 may be used to drive a source of hydraulic oil or fluid, so as to provide a governor effect to the braking action of the present invention where the brake force applied to drive shaft 14 is a function of the torque output of the prime mover.

    Thus, the lower the revolutions per minute RPM's , the smaller the load absorption applied to rotating shaft 14 by dynamometer The operation and configuration of the braking assembly of dynamometer 10 is described in greater detail below. In addition, chain sprocket 20 may be utilized to drive a coolant pump not shown for circulating a liquid coolant in dynamometer 10 in providing heat dissipation therein proportional to the applied braking force.

    Finally, chain sprocket 20 may be employed to drive a tachometer not shown to provide the operator with the speed of revolution of the prime mover. Moving toward the right with reference to FIG. In contact with inner race 32 is a self-aligning bearing assembly 36 which is maintained in contact with inner race 32 by means of an outer race 34 located around the periphery thereof.

    Outer race 34 is, in turn, fixedly positioned within ball bearing housing 30 which abuts and extends through an aperture in a first lateral wall 40 of a tank Thus, the combination of inner race 32, self-aligning bearing 36, outer race 34 and ball bearing housing 30 permits drive shaft 14 to be rotated while tank 42 remains essentially stationary. Tank 42 includes a second lateral wall 44 in facing relation to the first lateral wall Positioned around the periphery of ball bearing housing 30 and between this housing and a stationary support 56 is tank cradle bearing Thus, the tank is rotatable both with respect to the stationary support 56 and the drive shaft The other end of tank 42 is rotationally positioned upon stationary support 58 in a manner described in detail below.

    Stationary supports 56, 58 are rigidly affixed to support platform 64 by means of bolts 60, 62, respectively. Support platform 64 thus provides a stable, rigid mounting base for dynamometer Within tank 40 the drive shaft 14 is enclosed in a race 41 with double seals 38 positioned in sealing relation between race 41 and that portion of ball bearing housing 30 which extends into tank Double seals 38 thus provide for the confinement of a coolant liquid within tank 42 while permitting the free rotation of drive shaft 14 within tank Tank 42 includes a cover 48 securely positioned on and in sealing contact with first and second lateral walls 40, 44 by means of gasket seals 50, 52, respectively.

    Tank 42, of course, includes additional lateral walls not shown in FIG. On the other end portion of race 41 is positioned on the periphery thereof and in close contact therewith a coupling flange Coupling flange 74 is fixedly mounted on the right end of drive shaft 14 as viewed in FIG.

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    Flange 74 is, in turn, rigidly coupled by means of bolts 72 to a first lateral wall 76 of a first brake chamber Thus, with first brake chamber 78 rigidly coupled to flange 74 which, in turn, is fixedly coupled to drive shaft 14, the rotation of drive shaft 74 by a prime mover will result in the corresponding rotation of first brake chamber Flange 74 tightly encompasses drive shaft 14 and race 41 in preventing the flow of coolant liquid 31 from tank 42 into first brake chamber A silicon sealant is also utilized at all spline connections in contact with water.

    The first lateral wall 76 of first brake chamber 78 is coupled to a lateral portion thereof by means of a plurality of bolts First brake chamber 78 includes a second lateral wall 82 which is rigidly coupled by means of bolts 90 to a first lateral wall 84 of a second brake chamber Second brake chamber 86, in turn, includes a second lateral wall 88 coupled by means of a plurality of bolts 92 to a lateral portion of second brake chamber In this manner, a plurality of such brake chambers may be positioned along the axis of drive shaft 14 to provide increased energy absorption capacity such as for measuring the power of a prime mover.

    Included in first and second brake chambers 78, 86 are stator shafts 98, , respectively, which are aligned with drive shaft Lateral walls 82, 84 include an aperture therein through which the stator shafts 98, extend and in which they are coupled by means of splined keying elements inserted in surface slots in the respective stator shafts.

    In addition, a hydraulic connector couples the two stator shafts. The rear portion of dynamometer 10, or that to the right of FIG.

    Positioned immediately outward from ball bearing and along stator shaft is sleeve Seals are positioned between the inner portion of rear housing and sleeve to prevent the escape of liquid coolant from tank In addition, a cartridge face-type seal is positioned between stator shaft and sleeve to prevent the escape of lubricant from second brake chamber A retaining shoulder is positioned between ball bearing and sleeve to insure the proper seating and continued tight fit of the sleeve and associated concentrically placed seals about stator shaft Positioned within the stator shafts and extending the length thereof is a stator hydraulic control line which is coupled by means of pressure seal to a hydraulic pressure source control line The present invention envisions the use of any conventional source of hydraulic pressure which in FIG.

    Aligned, adjacent sections of control line in stator shafts 98 and are coupled in a sealed manner by hydraulic connection The present invention does not suffer from these limitations in that it offers a Prony brake type of load absorption unit, or dynamometer with conventional measuring instrumentation coupled thereto, which has a circulating, closed lubrication system which not only substantially extends the usable lifetime of the components therein, but also allows the unit to achieve larger loading capacities without the need for increasing the unit's heat dissipation capacity.

    The brake assembly is enclosed in a sealed drum coupled to a rotating shaft and rotationally displaced thereby within a water-filled tank. Friction engaging surfaces positioned within the drum adjacent to its lateral surface are displaced radially outward by means of a plurality of opposed, hydraulically-actuated brake shoes symmetrically positioned about the axis of rotation.

    Frictional heat buildup is transferred via the thin, finned metallic lateral surface of the drum to the surrounding water reservoir, which may be either closed or circulating in nature. A closed lubrication system circulates a lubricant within the brake cell to provide a suitable coefficient of friction between the engaging surfaces at high operating temperatures without lubricant loss from the brake drum due to "cook off".

    By means of this improved, closed lubrication system and by completely submerging the brake assembly in the water-filled tank, excessively high water temperatures are avoided with system safety thus enhanced and water cooling requirements substantially reduced.

    In a preferred embodiment, a silicon lubricant is utilized within the brake drum and is continually circulated over the friction engaging surfaces for improved brake operation. Provision is also made for the continuous filtering of the lubricant for the removal of displaced friction material therefrom.

    In the circulating lubrication system the lubricant is temporarily "trapped" away from the heated surfaces and then allowed to flow into the internal parts of the brake unit.

    The lubricant is then displaced from the friction engaging surfaces where maximum heating occurs by the rotation of the drum for improved brake cooling and limiting the operating temperature of the lubricant.

    However, the invention itself, as well as further objects and advantages thereof will best be understood by reference to the following detailed description of a preferred embodiment taken in conjunction with the accompanying drawings, where like reference characters identify like elements throughout the various figures, in which: FIG. A prime mover not shown is coupled to a universal yoke 12 which includes a shaft portion Shaft portion 13 is keyed so as to engage an outer flange 15 which, in turn, rotates with universal yoke 12 in response to the action of the prime mover.

    Outer flange 15 is rigidly coupled to inner flange 16 by means of a shear bolt Inner flange 16 is, in turn, fixedly coupled to drive shaft 14 by means of recessed keying portions Thus, drive shaft 14 rotates in response to the rotation of universal yoke 12 by virtue of the shaft coupling provided by linked outer and inner flanges 15, 16 and their respective shaft keying elements.

    Shear bolt 17 provides for the rapid disconnection of the drive shaft 14 from the universal yoke 12 in the event of an abnormal operating condition such as in the application of excessive torque values by the prime mover upon drive shaft Fixedly coupled to drive shaft 14 by means of keying elements 18 inserted in the drive shaft are outer and inner spacers 22, Positioned between spacers 22, 24 is a sprocket wheel 20 having a plurality of teeth around its periphery which are engaged by a flexible link chain Drive sprocket 20 may be used to drive a source of hydraulic oil or fluid, so as to provide a governor effect to the braking action of the present invention where the brake force applied to drive shaft 14 is a function of the torque output of the prime mover.

    Thus, the lower the revolutions per minute RPM's , the smaller the load absorption applied to rotating shaft 14 by dynamometer The operation and configuration of the braking assembly of dynamometer 10 is described in greater detail below.

    In addition, chain sprocket 20 may be utilized to drive a coolant pump not shown for circulating a liquid coolant in dynamometer 10 in providing heat dissipation therein proportional to the applied braking force.

    Finally, chain sprocket 20 may be employed to drive a tachometer not shown to provide the operator with the speed of revolution of the prime mover. Moving toward the right with reference to FIG. In contact with inner race 32 is a self-aligning bearing assembly 36 which is maintained in contact with inner race 32 by means of an outer race 34 located around the periphery thereof. Outer race 34 is, in turn, fixedly positioned within ball bearing housing 30 which abuts and extends through an aperture in a first lateral wall 40 of a tank Thus, the combination of inner race 32, self-aligning bearing 36, outer race 34 and ball bearing housing 30 permits drive shaft 14 to be rotated while tank 42 remains essentially stationary.

    Tank 42 includes a second lateral wall 44 in facing relation to the first lateral wall Positioned around the periphery of ball bearing housing 30 and between this housing and a stationary support 56 is tank cradle bearing Thus, the tank is rotatable both with respect to the stationary support 56 and the drive shaft The other end of tank 42 is rotationally positioned upon stationary support 58 in a manner described in detail below.

    Stationary supports 56, 58 are rigidly affixed to support platform 64 by means of bolts 60, 62, respectively. Support platform 64 thus provides a stable, rigid mounting base for dynamometer Within tank 40 the drive shaft 14 is enclosed in a race 41 with double seals 38 positioned in sealing relation between race 41 and that portion of ball bearing housing 30 which extends into tank Double seals 38 thus provide for the confinement of a coolant liquid within tank 42 while permitting the free rotation of drive shaft 14 within tank Tank 42 includes a cover 48 securely positioned on and in sealing contact with first and second lateral walls 40, 44 by means of gasket seals 50, 52, respectively.

    Tank 42, of course, includes additional lateral walls not shown in FIG. On the other end portion of race 41 is positioned on the periphery thereof and in close contact therewith a coupling flange Coupling flange 74 is fixedly mounted on the right end of drive shaft 14 as viewed in FIG.

    Flange 74 is, in turn, rigidly coupled by means of bolts 72 to a first lateral wall 76 of a first brake chamber Thus, with first brake chamber 78 rigidly coupled to flange 74 which, in turn, is fixedly coupled to drive shaft 14, the rotation of drive shaft 74 by a prime mover will result in the corresponding rotation of first brake chamber Flange 74 tightly encompasses drive shaft 14 and race 41 in preventing the flow of coolant liquid 31 from tank 42 into first brake chamber A silicon sealant is also utilized at all spline connections in contact with water.

    The first lateral wall 76 of first brake chamber 78 is coupled to a lateral portion thereof by means of a plurality of bolts First brake chamber 78 includes a second lateral wall 82 which is rigidly coupled by means of bolts 90 to a first lateral wall 84 of a second brake chamber Second brake chamber 86, in turn, includes a second lateral wall 88 coupled by means of a plurality of bolts 92 to a lateral portion of second brake chamber In this manner, a plurality of such brake chambers may be positioned along the axis of drive shaft 14 to provide increased energy absorption capacity such as for measuring the power of a prime mover.

    Included in first and second brake chambers 78, 86 are stator shafts 98, , respectively, which are aligned with drive shaft Lateral walls 82, 84 include an aperture therein through which the stator shafts 98, extend and in which they are coupled by means of splined keying elements inserted in surface slots in the respective stator shafts. In addition, a hydraulic connector couples the two stator shafts. The rear portion of dynamometer 10, or that to the right of FIG. Positioned immediately outward from ball bearing and along stator shaft is sleeve Seals are positioned between the inner portion of rear housing and sleeve to prevent the escape of liquid coolant from tank In addition, a cartridge face-type seal is positioned between stator shaft and sleeve to prevent the escape of lubricant from second brake chamber A retaining shoulder is positioned between ball bearing and sleeve to insure the proper seating and continued tight fit of the sleeve and associated concentrically placed seals about stator shaft Positioned within the stator shafts and extending the length thereof is a stator hydraulic control line which is coupled by means of pressure seal to a hydraulic pressure source control line The present invention envisions the use of any conventional source of hydraulic pressure which in FIG.

    Aligned, adjacent sections of control line in stator shafts 98 and are coupled in a sealed manner by hydraulic connection Positioned immediately adjacent to rear housing is rear bearing mount upon which is positioned a tank cradle bearing The tank cradle bearing is positioned within support 58 for allowing a limited degree of rotation of the tank 42 about its longitudinal axis. Coupled to stator shaft is a torque pick off arm by means of which the torque applied to the stator shafts by the braking mechanism of dynamometer 10 may be measured and provided to a conventional torque indicating means The manner in which the torque is transmitted by the brake mechanism to the stator shafts is described below.

    Dynamometer: Introduction and Types

    The operation of dynamometer 10 will now be described with reference to FIGS. The first and second brake chambers 78, 86 operate in an identical manner and the following discussion will therefore be limited primarily to describing the configuration and operation of first brake chamber Referring to FIGS. A cylinder block casting is positioned around and integral with stator shaft Provided in cylinder block casting are a plurality of cylinders symmetrically positioned with respect to the axis of stator shaft Pistons are positioned in mutually opposing relation on opposite sides of stator shaft 98 in these cylinders.

    In a preferred embodiment of the present invention, four symmetrically positioned pistons are located in each brake chamber. Each piston is connected to a hydraulic control line which, in turn, is coupled to the stator hydraulic control line Thus, the pistons are responsive to changes in hydraulic pressure as provided by a brake controller not shown.

    With an increase in hydraulic pressure in the system, the pistons will be displaced radially outward from the axis of stator shaft A drive pin is press-fit into stator shaft 98 and cylinder block casting for securely coupling these structures as a unit. Surrounding each piston is a brake shoe casting which contacts a backup plate The outward displacement of piston and brake shoe casting results in the corresponding outward displacement of brake lining The outward displacement of brake lining places it in engaging contact with drum lateral wall whereby a braking action is applied to the rotating drum in providing a counteracting force against the torque of the prime mover.

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