102results about "Cranks" patented technology

The invention is suitable for the field of cycloidal speed reducers, and provides an RV speed reducer which comprises a shell assembly, an input assembly and a speed reduction assembly and is characterized in that the shell assembly comprises a front supporting shell, a rear supporting shell, a positioning bolt and a positioning shaft, and the front supporting shell and the rear supporting shell are fixedly installed through the positioning bolt; positioning holes are annularly formed in the supporting front shell and the supporting rear shell, the positioning shaft is installed in the positioning holes in a rolling mode, the speed reduction assembly comprises a speed reduction sealing cover, a planet assembly and a main speed reduction assembly, the speed reduction sealing cover is installed in the supporting front shell through a bearing, and the circle center of the speed reduction sealing cover coincides with the circle center of the supporting front shell; and the kinetic energy transmission efficiency and the maximum running speed are improved, so that the joint is more suitable for high-speed robot speed reduction joints. Pitting corrosion, micro pitting corrosion and eccentric wear of the balance wheel are avoided, and the service life of the speed reduction assembly is prolonged.

An assembly is provided including a pin and a crank. The crank has a hole in which a connecting region of the pin is fixed by an interference fit to connect the pin and the crank. The hole has a substantially circular cross-section and the connecting portion has a circular cross-section. The cross-section of the hole deviates from the circular shape at one or more places and is larger at any such locations than the cross-section of the connecting portion.

The invention discloses a crankshaft assembly of an engine, the engine and a vehicle, and relates to the technical field of engines, the crankshaft assembly comprises a crankshaft, a first rolling bearing, a second rolling bearing and a sliding bearing, the crankshaft comprises a plurality of crankshaft body sections and a connecting rod journal section, and the crankshaft body sections are sequentially arranged at intervals in the length direction of the crankshaft; a connecting rod journal section is connected between any two adjacent crankshaft body sections, at least one crankshaft body section is sleeved with a first rolling bearing, the first rolling bearing is used for being connected with an engine body of an engine, the connecting rod journal section is sleeved with a second rolling bearing, and the second rolling bearing is used for being connected with a crankshaft connecting rod of the engine. At least one crankshaft body section is sleeved with a sliding bearing, and the sliding bearing is used for being connected with an engine body. According to the crankshaft assembly, the energy loss can be reduced, the mechanical loss of an engine is effectively reduced, and the efficiency of the engine is improved.

The utility model relates to a transmission mechanism of a pump body, in particular to a connecting rod shaft assembly which comprises a connecting rod shaft (1), one end of the connecting rod shaft (1) is connected with an eccentric wheel (2), the middle of the connecting rod shaft (1) is connected with a bearing (4), the upper end face of the eccentric wheel (2) is attached to the lower end face of the bearing (4), and the outer ring of the bearing (4) is connected with a piston rod (3). The eccentric wheel (2) drives the connecting rod shaft (1) to rotate so that the piston rod (3) can move linearly, and the movement track of the piston rod (3) is perpendicular to the central axis of the connecting rod shaft (1). The connecting rod shaft assembly can be connected with the connecting rod shaft through the eccentric wheel, the connecting rod shaft is provided with the bearing, and the bearing is attached to the eccentric wheel, so that the stress arm can be reduced, and the service life of the connecting rod shaft is prolonged.

Arrangement for driving an adjusting shaft (2) for adjusting the expansion stroke and / or the compression ratio of an internal combustion engine (1), wherein the arrangement has a drive motor (11) which is or can be connected to the adjusting shaft (2) via a gear mechanism, characterized in that the gear mechanism is designed as a tension wave gear mechanism (13) with a wave generator (14), an externally toothed flexspline (16) and an internally toothed ring gear meshing with the flexspline (16), and is arranged in a gear housing (22) which is or can be fastened to the crankcase (25) of the internal combustion engine (1) in such a way that the flexspline (16) always remains in the same rotational position relative to the gear housing (22), wherein the tension wave gear mechanism (13) is designed to transmit a torque to the adjusting shaft (2), the coupling end of which executes an axial and / or radial movement in an externally driven manner,an output element (35) comprising the ring gear, which is torsionally rigid and at the same time flexible and at least partially, in particular completely, decouples the flexspline (16) from the externally driven axial and / or radial movement.

The invention discloses a crankshaft assembly of an engine, the engine and a vehicle, and relates to the technical field of engines, the crankshaft assembly comprises a crankshaft and a rolling bearing, the crankshaft comprises a plurality of crankshaft body sections and a connecting rod journal section, and the crankshaft body sections are sequentially arranged at intervals in the length direction of the crankshaft; a connecting rod journal section is connected between any two adjacent crankshaft body sections, an oil flow channel is formed in the crankshaft and used for being arranged corresponding to an oil supply port in an engine body, each connecting rod journal section is sleeved with a rolling bearing, the rolling bearings are used for being connected with a crankshaft connecting rod of an engine, oil inlet holes are formed in the rolling bearings, and the oil inlet holes are communicated with the oil inlet holes. And the oil inlet hole is communicated with the oil flow channel. According to the crankshaft assembly, the energy loss can be reduced, the mechanical loss of an engine can be reduced, the efficiency of the engine can be improved, the effect of lubricating the multiple rolling bearings at the same time can be achieved by arranging the oil flow channel in the crankshaft, and the lubricating effect of the crankshaft assembly can be improved.

The application discloses an adjustable crank structure, which comprises an adjusting block mounting seat, an eccentric adjusting block connected to the adjusting block mounting seat, a rotating axis of the adjusting block mounting seat being parallel to a center line of the eccentric adjusting block with a spacing formed between the rotating axis and the center line, and a motion characteristic of the structure being changed by adjusting the spacing, a connecting rod rotatably connected to the eccentric adjusting block, the connecting rod being capable of reciprocating under the driving of the eccentric adjusting block, power transmission and motion conversion being realized, a connecting shaft assembly hinged with the connecting rod, the connecting shaft assembly being used for connecting a target force receiving shaft, and two adjusting bolts screwed into specific threaded holes of the adjusting block mounting seat and abutting against specific parts of the eccentric adjusting block. The adjusting bolts are rotated and moved along specific directions on the adjusting block mounting seat, the spacing is adjusted by the two adjusting bolts, and thus flexible adjustment of motion parameters of the crank structure is realized.

The utility model relates to the technical field of crankshaft transmission structures, in particular to a high-precision crank pin shaft which comprises a crank connecting piece, and a first connecting sleeve is embedded in one side of the crank connecting piece. When the crank pin shaft is installed, the anti-friction layer in the crank connecting piece and the sliding block connecting sleeve at the other end of the crank pin shaft are aligned with the rotating disc and the sliding block to be installed in an embedded mode, then lubricating oil is injected into the lubricating oil bin, then the sealing cover is inserted, the sealing inserting piece seals an oil injection opening of the lubricating oil bin, and then the anti-friction layer is embedded into the rotating shaft. Then the first connecting sleeve is inserted into a groove of a crank connecting piece, a positioning rotary knob is rotated to push a movable clamping piece at the bottom end of a movable telescopic piece to slide, and the movable clamping piece is inserted into a connecting clamping groove in the side wall of the first connecting sleeve to complete clamping and fixing; the transmission rod moves to drive the sliding block connecting piece to move, and therefore the sliding block connected with the sliding block connecting sleeve is pushed to move linearly.

The invention relates to an assembly (1, 2) comprising a pin (2) and a crank (1), in particular for a turbocharger, the crank (1) having a bore (12) in which a connecting portion (21) of the pin (2) for connecting the pin (2) with the crank (1) is fixed by an interference fit, wherein the bore (12) has a substantially circular cross-section and the connecting portion (21) has a circular cross-section, the cross-section of the bore (12) deviating from the circular shape at at least one location (121) and being larger than the cross-section of the connecting portion (22) at this location (121).

An assembly of a crankshaft and a connecting rod, the crankshaft being rotatable about a crankshaft axis and comprising a crank pin (5) and a pair of crank webs (6). The connecting rod comprising a big end (10) connected to the crank pin by a big end bearing (11) located between the pair of crank webs and a small end for connecting the connecting rod to a piston. A reservoir (21) for lubricating oil being provided between the big end and the crank pin and a jetting passage (30) being provided for jetting, in use, a piston cooling jet of lubricating oil from the reservoir towards a back face of a piston connected in use to the small end of the connecting rod. The jetting passage comprising two cut-outs, a first cut-out (32) located in a side face (18) of the big end and a second cut-out (33) located in an inwardly-directed side face (19) of the crank web that faces said side face of the big end, the second cut-out defining an outlet (34) of the jetting passage. The first cut-out extends from an inner edge (36) of the side face only part way towards an outer edge (37) of the side face and the second cut-out extends from the outlet at an outer edge (38) of the inwardly-directed side face only part way towards an inner edge (39) of the inwardly-directed side face, such that the jetting passage is established when rotation of the big end about the crank pin overlaps the first cut-out with the second cut-out.

The utility model discloses a modularized crankshaft and an RV speed reducer, and belongs to the field of speed reducers. The shape memory alloy assembly is sleeved outside the central shaft; the first shaft sleeve assembly and the second shaft sleeve assembly are detachably connected outside the shape memory alloy assembly in a sleeving mode, and the first shaft sleeve assembly abuts against the second shaft sleeve assembly. The first shaft sleeve assembly and the second shaft sleeve assembly are the same in structure and each comprise a first shaft sleeve body detachably connected to the outside of the shape memory alloy assembly in a sleeving mode. And the second shaft sleeve body is sleeved outside the first shaft sleeve body. A first flat potential is arranged outside the first shaft sleeve body, a second flat potential is arranged in the second shaft sleeve body, and the first flat potential abuts against the second flat potential. The utility model has the technical effects that the modular performance is good, and the connection performance is good.

A gear motor of an electrical assistance device, in particular for a cycle, includes a gear reducer and an electric motor including a stator and a rotor integral in rotation with a shaft forming the input of the gear reducer. The gear reducer includes a toothed crown integral with the stator, a satellite-carrier fitted to pivot around the shaft, and forming the output of the gear reducer, at least two planet wheels fitted firstly on respective eccentric cams via a respective bearing. The ge ar motor also includes a rotor bearing to center a first end of the shaft on a fixed shaft of the gear motor, and a bearing device including deformable rolling elements. The bearing device is interposed between the satellite-carrier and a cylindrical receptacle which is integral with the stator, to center the shaft in the cylindrical receptacle at a second end.

The utility model provides a high oil pressure crank pin assembly, which relates to the technical field of crank pins, and comprises a crank pin, an installation disc is fixedly installed between the inner walls of the crank pin, a bowl-shaped plug is installed between the inner walls of the crank pin, the lower end of the bowl-shaped plug is attached to the upper surface of the installation disc, a positioning assembly is arranged in the bowl-shaped plug, and the positioning assembly is connected with the installation disc. The bowl-shaped plug is connected with the crank pin through a positioning assembly, a clamp spring groove is formed in the inner wall of the crank pin, and a clamp spring is arranged in the clamp spring groove. The bowl-shaped plug is installed in the crank pin, when high-pressure oil abuts against the plug, the clamp spring abuts against the plug, the high-pressure oil cannot leak, and then the assembled crank pin assembly is connected with the crank pin through the clamp spring. By means of the arrangement, the sealing performance of the crank pin oil hole is obviously improved, the rigid plug is not prone to disengaging from the plug containing section even under the high pressure condition, meanwhile, the rigid bowl-shaped plug is not prone to being affected by systematic changes of the hole diameter, and the problem that lubricating oil matched with a crankshaft assembly leaks is solved.

A crankshaft (1, 40) for an internal combustion engine including variable compression ratio comprises a main journal, a first crankpin (3a, 43a), a first and second crank web (4a, 4b, 44a, 44b) at opposite sides of the first crankpin (3a, 43a), a second crankpin (3b, 43b) and a third and fourth crank web (4c, 4d, 44c, 44d) at opposite sides of the second crankpin (3b, 43b) The crankshaft also includes a first eccentric member (6a, 45a) which is rotatably mounted on the first crankpin (3a, 43a) and a second eccentric member (6b, 45b) which is rotatably mounted on the second crankpin (3b, 43b) and a transfer shaft (19, 50) which extends through the second and third crank web (4b, 4c, 44b, 44c) and which is rotatable with respect to the second and third crank web (4b, 4c, 44b, 44c) about a transfer shaft axis. An external first transfer gear (18, 52) is fixed to the transfer shaft (19, 50) at a side of the second crank web (4b, 44b) where the first eccentric member (6a, 45a) is located and an external second transfer gear (21, 49) is fixed to the transfer shaft (19, 50) at a side of the third crank web (21, 44c) where the second eccentric member (6b, 45b) is located. The first and second eccentric members (6a, 6b, 45a, 45b) are drivably coupled to each other through the transfer shaft (19, 50). The first and second transfer gears (18, 21, 47, 48) mesh with external first and second intermediate transfer gears (17, 22, 51), respectively, which in turn mesh with the first and second eccentric member gears (10, 23, 47, 48). The first and second intermediate transfer gears (17, 22, 51) are rotatably mounted to the second and third crank webs (4b, 4c, 44b, 44c), respectively.

The bicycle crank assembly comprises a transmission middle shaft, a left crank module and a right crank module are formed at the left end and the right end of the transmission middle shaft respectively, and a bearing set is arranged at the middle end of the transmission middle shaft; the transmission middle shaft is sleeved with a pre-pressing ring close to the left crank module. Wherein the pre-pressing ring is attached to the left crank module to form an initial position; the pre-pressing ring abuts against the bearing set to form a locking position. And the jacking mechanism comprises a jacking piece and at least one guide hole formed in the left crank module, and the guide hole axially extends towards the transmission middle shaft. According to the technical scheme, the axial constraining force is applied to the pre-pressing ring, so that the pre-pressing ring is always kept at the locking position, the phenomenon that the pre-pressing ring is reversed and loosened is prevented, unnecessary cost expenditure caused by collision damage of the bicycle bottom bracket and accessories is effectively avoided, certain potential safety hazards are solved, and the safety of the bicycle is improved.

A rotary body (30) according to the present invention is made of resin and attached to a crankshaft (20). The rotary body (30) has an outside plate element (32) and an inside plate element (36) which are attached to an outside surface (24a) and an inside surface (24b) of an arm portion (24) of the crankshaft, respectively, and a pair of filler elements (34) disposed between the outside plate element and the inside plate element and on both sides of the arm portion. The outside plate element and the pair of the filler elements are coupled to each other, and the pair of the filler elements and the inside plate element are coupled to each other.

The invention provides a two-stage compression air compressor, and belongs to the technical field of air compressors. The two-stage oil-free air compressor solves the technical problems that an existing two-stage oil-free air compressor is remarkable in vibration due to unbalanced movement of a piston, fixed in output pressure and lack of adjustment flexibility. The air compressor comprises a driving motor, wherein two output shaft sections of the driving motor respectively drive two first-stage air cylinder assemblies located on the same side of the motor and two second-stage air cylinder assemblies located on the other side of the motor at the same time; the corresponding air cavities of the air cylinder assemblies on the two sides communicate with each other, and the first-stage air outlet cavity and the second-stage air inlet cavity are connected through an intercooling air pipe. Through the opposite arrangement of the two first-stage cylinders and the two second-stage cylinders and the specific phase design, reciprocating inertia force is counteracted in real time, and vibration and noise are greatly reduced; meanwhile, by means of the parallel connection characteristic of the systems on the two sides, the output pressure and power can be conveniently adjusted by controlling operation of the motor on the single side. The device has the advantages of being stable in operation, high in reliability, adjustable in pressure output and high in adaptability.

To facilitate assembly work and inhibit uneven contact between a gear shaft and a gear configured to engage with the gear shaft even if an inclination occurs between the gear shaft and the gear.SOLUTION: A compression ratio variable device 10a includes a gear shaft 52 which has a shaft 55 including a gear 51 for rotating an eccentric cam 31 and forms a power transmission member between a power source 32 and the eccentric cam 31. The shaft 55 and the gear 51 are formed separately. The shaft 55 has a spline shaft 55a, configured to fit in a spline hole 51a provided at the gear 51, at one end.SELECTED DRAWING: Figure 4

The utility model provides an eccentric mechanism of an air compressor, and belongs to the technical field of air compressors. The air compressor solves the problems that an existing air compressor is low in acting efficiency, and stress is unbalanced when a main shaft works. The eccentric mechanism of the air compressor comprises a main shaft, one end of the main shaft is sleeved with a first eccentric wheel, a second eccentric wheel, a third eccentric wheel and a fourth eccentric wheel, and the first eccentric wheel, the second eccentric wheel, the third eccentric wheel and the fourth eccentric wheel are freely and smoothly arranged in the axial direction of the main shaft. The second eccentric wheel deflects around the main shaft by an angle alpha which is larger than or equal to 0 degree and smaller than or equal to 180 degrees relative to the first eccentric wheel, the third eccentric wheel deflects around the main shaft by 180 degrees relative to the first eccentric wheel, and the fourth eccentric wheel deflects around the main shaft by 180 degrees relative to the second eccentric wheel. According to the structure, the vibration and noise of the whole machine during working are reduced, the working efficiency of the air compressor is improved, the arrangement of the four eccentric wheels on the main shaft can be changed in any sequence according to the structural design of the air compressor, and the position arrangement flexibility of the four eccentric wheels is improved.

The present invention discloses a detection method and system for the assembly process of a crank connecting rod mechanism, including: obtaining the tolerance values of the historical assembly of each component in the crank connecting rod mechanism, thereby constructing an assembly process detection library; using a hybrid clustering algorithm to cluster the assembly process detection library to determine the normal process assembly threshold and the abnormal process assembly threshold; the hybrid clustering algorithm includes optimizing each particle in the particle swarm algorithm within the decision domain range, and the decision domain range is corrected according to the ratio of the difference between the fitness values of the k-th iteration step and the k + 1-th iteration step to the fitness value of the k-th iteration step; obtaining the tolerance values of the actual assembly of each component in the crank connecting rod mechanism, and comparing them with the normal process assembly threshold and the abnormal process assembly threshold to determine the normal or abnormal state of the assembly process of the crank connecting rod mechanism, effectively improving the engine assembly accuracy.

The utility model relates to the technical field of robots, and discloses a crank, a transmission structure of a biped robot, a humanoid robot and a robot. According to the transmission crank, the mounting groove is formed in the shaft section, the bearing is assembled in the mounting groove through the outer ring, and the end, away from the joint module, of the crank is dynamically supported through the bearing. According to the embodiment, the mounting groove is formed in the shaft section of the crank, so that the bearing can be directly mounted in the mounting groove of the crank shaft section instead of being sleeved outside the shaft section of the supporting piece. The cost of the transmission crank can be reduced.

The utility model discloses an eccentric wheel structure which comprises an upper ring body and a lower ring body, the upper ring body is arranged above the lower ring body, a connecting hole is formed in the center of the upper ring body and the center of the lower ring body, an outer ring on one side of the upper ring body is a perfect circular arc, an outer ring on the other side of the upper ring body is a non-perfect circular arc, and a semicircular disc-shaped protruding block corresponding to the non-perfect circular arc is arranged on the lower ring body. A plurality of grooves are formed in the connecting hole; the whole body is integrally formed through metal powder sintering. The eccentric wheel is reasonable and ingenious in structural design, the integrally-formed structure is high in structural strength, the contact face of the connecting part is increased due to superposition of the upper ring body and the lower ring body, the eccentric wheel is not prone to deformation, and the performance of the eccentric wheel is improved.

An adjustment device (4) is connected to a transmission device (33) of a thread rolling machine (3). The transmission device (33) includes an eccentric wheel (332) and a transmission shaft (333). The adjustment device (4) includes a drive assemblage (42) and a worm assemblage (43) linked with the transmission shaft (333). The worm assemblage (43) includes a worm shaft (431) meshed with the drive assemblage (42) and a regulating unit (433) disposed on the worm shaft (431). The drive assemblage (42) includes a first drive unit (421) disposed on a first shaft end (333A) of the transmission shaft (333) and defining a positioning portion (422) whose center is situated away from a center of the first drive unit (421) to present an eccentric arrangement. Accordingly, the cooperation between the drive assemblage (42) and the worm assemblage (43) allows a thread-rolling distance applied to the thread rolling machine (3) to be easily and precisely adjusted.

An assembly of a connecting rod and a crankshaft including a pair of crank webs 6 and a crank pin 5. A reservoir 21 for lubricating oil between a big end 10 of the conrod and the crank pin, and a jett

The utility model relates to the technical field of compressors, and discloses a crankshaft of a reciprocating compressor, which comprises a main journal, balance blocks are fixedly mounted on two sides of the main journal, a first piston rod journal is fixedly mounted on one side, far away from the main journal, of each balance block, and a second connecting handle is fixedly mounted on one side, far away from the corresponding balance block, of each first piston rod journal. A crank is fixedly installed on the side, away from the first piston rod journal, of the second connecting handle, and a second piston rod journal is fixedly installed on the side, away from the second connecting handle, of the crank. Through cooperative use of an oil liquid injection groove and an oil liquid storage groove, the outer edges of the first piston rod journal and the second piston rod journal need to be lubricated, so that when the first piston rod journal and the second piston rod journal are slidably connected with the piston rod in a sleeving mode more smoothly, the first piston rod journal and the second piston rod journal need to be lubricated before the first piston rod journal and the second piston rod journal are not connected with the piston rod; lubricating oil is poured into the inner wall of the oil storage tank through the oil injection tank.

The utility model relates to the field of eccentric blocks, in particular to a high-strength eccentric block for an automobile air conditioner compressor, which comprises a main shaft. A protection assembly is arranged on the outer wall of the spindle. The upper end of the main shaft is fixedly connected with an eccentric block; an eccentric shaft is installed on the eccentric block in a threaded mode. Main body structures of all the components are made of high-strength aluminum alloy, the mechanical performance is excellent, meanwhile, the eccentric block is protected from the outside through the protection shell, resistance and friction force borne by the eccentric block when the eccentric block rotates eccentrically on the inner wall of the protection shell are reduced through the pin rollers, and the service life of the eccentric block is prolonged. The eccentric block is not prone to abrasion or deformation in the long-term use process, the clamping block and the clamping groove are arranged between the eccentric block and the main shaft for mutual limiting, stable connection between the eccentric block and the main shaft is achieved through the bolt and the hollow stud, and meanwhile the structure easy to disassemble and assemble is beneficial to maintenance and replacement of all assemblies.

The utility model discloses an eccentric wheel structure of a fireproof spraying machine, which comprises a spraying machine shell, a hyperboloid gear reducer arranged in the spraying machine shell, two side plate brackets arranged on one side in the spraying machine shell, a first rotating shaft rotationally connected between the two side plate brackets through a bearing, and an eccentric wheel fixedly connected on the rotating shaft, a strip-shaped through groove is formed in the side plate support, rolling bearings are arranged in the strip-shaped through groove, a second rotating shaft is rotationally connected between the two rolling bearings, a coupling sleeve is fixedly connected to the second rotating shaft, and the position, away from the first rotating shaft, of the eccentric wheel is connected with the second rotating shaft. A plunger rod is arranged at the bottom of the coupling sleeve; the spraying device has the advantages that the eccentric wheel is driven to rotate through the double-curved-surface gear reducer, so that the second rotating shaft reciprocates up and down in the strip-shaped through groove, the plunger rod is driven to reciprocate, opening and closing of the valve can be more accurately controlled, and starting and stopping of spraying are accurately adjusted.

An adjustable transmission element (1) comprises a drive motor (2) provided with a rotating shaft (3) associated with a crank (4) which in turn is pivoted to a first end (5a) of a link rod (5) which has a second end (5b) which is pivoted to a sliding sled (6). An adjustable interconnection apparatus (8) is interposed between the shaft (3) of the motor (2) and the crank (4) and comprises: at least one cylindrical body (9), integral with the shaft (3), provided with first coupling means (10) and with at least one protruding stem (11) which is parallel to the shaft (3) and can move along a substantially radial stroke along the end face (9a) of the cylindrical body (9); at least one bell (13) provided with a cavity (14) with a shape substantially complementary to that of the cylindrical body (9), for its accommodation, and with second coupling means (15), complementary to the first coupling means (10), for the mechanical connection of the bell (13) to the cylindrical body (9) in a mutually coupled configuration. The bell (13) comprises a slot (16) in its end face which is substantially a spiral, regular or irregular, and is configured to accommodate the protruding stem (11). At least one actuator (17) configured for the translation of the bell (13) between a first configuration of partial separation from the cylindrical body (10), in which the first coupling means (10) and the second coupling means (15) are mutually facing, proximate, and not in mutual contact, and a second configuration of maximum proximity to the cylindrical body (9), in which the first coupling means (10) and the second coupling means (15) are in mutual contact, rendering the cylindrical body (9) and the bell (13) integral.

An adjustable stroke mechanism has a housing with a central axis and a wall enclosing a cavity. At least one counterweight is movably disposed within the cavity. A mounting assembly is disposed within the cavity. The mounting assembly has a workpiece attachment mechanism. A stroke adjustor couples the at least one counterweight with the mounting assembly. The stroke adjustor enables the counterweight and mounting assembly to move with respect to one another such that a distance between the counterweight and the mounting assembly is variably adjusted which, in turn, variably adjusts a stroke radius of the workpiece attachment mechanism with respect to the central axis of the housing.