Abstract: A surgical instrument and a battery pack for use with the surgical instrument are disclosed. The surgical instrument includes a handle assembly, having a protruding portion; and a battery pack, detachably assembled on the handle assembly, operated by the protruding portion, and having a battery unit, where the battery pack includes a discharging system comprising a discharge element, and a switching member, operated to electrically connect the discharge element to the battery unit of the battery pack to form a discharge circuit, and having an initial open state, in which the discharge circuit is non-conductive, an intermediate open state, in which the switching member cooperates with the protruding portion to make the discharge circuit non-conductive, and a closed state, in which the switching member is separated from the protruding portion to make the discharge circuit conducting.

Abstract: An apparatus for cutting pipes made of thermoplastic material, including: a tool for cutting pipes, an arm for supporting the tool which is movable between a non-operating configuration wherein the tool is disengaged from the pipe and an operating configuration wherein the tool is engaged in the pipe to exert a cutting action on the pipe, a lever which can be constrained to the arm, supporting device configured to move said lever, a locking unit for reversibly constraining said arm and said lever and disengaging means to move said arm from the operating configuration to the non-operating configuration.

Abstract: An electric motor (1), for a drive unit (2) of a drive train test bench, having a housing (3). The electric motor (1) is characterized in that the housing (3) has at least one yoke (4) for supporting the electric motor (1).

Abstract: The present invention provides a lathe having a speeder device to increase the speed of a workpiece to be worked on by the lathe as compared to the speed of a workpiece to be worked on by the lathe without the use of the speeder device. The speeder device includes a torque arm, a means for stopping rotation of the torque arm, a planetary gearset assembly, an output spindle assembly, and a collet assembly. The means for stopping rotation of the torque rod is secured to a first end of the torque rod and the planetary gearset assembly is operatively connected to a second end of the torque rod. The output assembly is operatively connected to the planetary gear assembly, and the collet assembly holds the workpiece and is operatively connected to the spindle assembly.

Abstract: An apparatus for cutting pipes made of plastic material in automatic cutter machines, including a tool for cutting pipes made of plastic material, a first rocker arm supporting the cutting tool, movable between a non-operating configuration at which the tool is disengaged from the pipe and an operating configuration wherein the tool is designed to exert its cutting action on the pipe, a second arm, for controlling the first arm, operatively connected to the first arm for moving it at least between its non-operating and operating configurations, the second arm comprising a first electric actuator and a supporting body slidably connected for modifying its reciprocal position between a close position and a spaced-apart position.

Abstract: An implant driver for engaging an orthopedic implant for selective advancement and retraction of the implant. The implant driver includes a first jaw assembly comprising a helical cam surface corresponding with a first direction of rotation. The first jaw assembly is operative to engage, in response to rotation in the first direction, the implant using spherical jaw members disposed in constrictive helical channels. The implant driver includes a second jaw assembly comprising a helical cam surface corresponding with a second direction of rotation. The second jaw assembly is operative to engage, in response to rotation in the second direction, the implant using spherical jaw members disposed in constrictive helical channels. Absent rotation of the first and second jaw assemblies, the spherical jaws may not restrict relative axial movement between the implant and the implant driver to allow for advancement and/or retraction of the instrument relative to the implant.

Abstract: A single use integrated disposable rotational speed reduction assembly having a shaft assembly, a housing, an output assembly, and a plurality of planetary gears each having a plurality of gear teeth. The shaft assembly is configured to cause rotation of the planetary gears with a sun gear. The rotation of the planetary gears is configured to cause rotation of an output shaft, with a reduction of rotational speed relative to the rotation of the shaft assembly. One or more gear components or spacers can be configured to fail after a predetermined number of use cycles.

Abstract: A power tool is provided including a motor housing; a transmission housing disposed adjacent the motor housing with a gap therebetween; an electric motor including a rotor and a stator mounted within the motor housing; and an intermediate housing disposed between the electric motor and the transmission mechanism. The intermediate housing includes a back wall extending radially adjacent an axial end of the stator and having a through-hole therein through which the motor spindle extends; side walls extending axially from an outer circumference of the back wall internally of the motor housing; and one or more external walls extending substantially-radially outwardly from axial end of the one or more side walls to fill a gap formed between the transmission housing and the motor housing in the axial direction.

Abstract: A power tool, such as an impact driver, includes a motor having a rotor that rotates relative to a stator, and a centrifugal fan that rotates together with the rotor. A motor housing and a rear housing house the motor. Overlapping parts of the motor housing and the rear housing radially surround an outer circumference of the centrifugal fan. Air exhaust ports are defined in each of the overlapping parts and are offset in an axial direction of the rotor. Fluid communication paths are defined between the air exhaust ports in the overlapping parts. The fluid communication paths have an opening area or width in the axial direction that is smaller than an opening area or width in the axial direction of the air exhaust ports.

Abstract: The present invention discloses an industrial high speed micro drill that is made to access remote and inaccessible locations in order to blend, grind, polish and cut materials and parts as determined by visual inspection powered via a pneumatic power source. The high speed drill is deployed by a controlled, articulating guide tube that acts in a multidirectional fashion to direct the action of the assemblage and allow for discrete manipulation of the pneumatically powered drill while harboring a channel and pneumatic power source carrying rubber tubing.

Abstract: A machine tool includes: a tool holder which includes a key groove; a spindle drive unit which includes a spindle key that can be fitted into the key groove of the tool holder and a spindle and which removably holds the tool holder; a tool exchanger which includes a grip key and a grip that holds the tool holder at a fixed position with respect to the spindle; and a numerical controller which controls the tool exchanger so as to fit and remove the tool holder with respect to the spindle, and the numerical controller controls the spindle drive unit such that when the tool holder is fitted to the spindle, in a state where the key groove of the tool holder is inserted in the spindle key, the spindle is rotated to press the spindle key to the key groove so as to determine the phase of the tool holder with respect to the spindle.

Abstract: A driving pump has an oil reservoir, a main assembly, a driving assembly, and a piston. The main assembly includes a first chamber, a second chamber, an exhaust channel, and an exhaust blockage. The exhaust channel communicates with the first chamber and the oil reservoir. When the piston is subjected to an outer reaction force and the driving assembly keeps pushing the first chamber, the oil and the gas in the first chamber may flow back to the oil reservoir. A clamping tool has the driving pump for controlling a clamp. Thus, even if the oil reservoir contains gas and the gas flows into the main assembly with the oil, the gas and the oil can be discharged back to the oil reservoir via the exhaust channel.

Abstract: A hand-held machine tool having a tool receiver to receive an insert tool having an external profile, the tool receiver featuring an internal receiver provided at least sectionally with an internal profile, and having a tool housing assigned a tool-change magazine having at least one tool chamber for storing the insert tool, the tool chamber being alignable with the tool receiver to allow the insert tool to be transferred from the tool chamber into the internal receiver or from the internal receiver into the tool chamber, a positioning device being provided for the circumferential alignment of the external profile when transferring the insert tool from the tool chamber into the internal receiver of the tool receiver to produce a form-locking connection between the internal profile and the external profile that at least for the most part, is free of rotational play, the positioning device has at least one magnet.

Abstract: A gear-driver adapter configured to switch between at least two gear ratios includes a switch which exerts a force on a drive shaft to move the drive shaft between at least two positions, each corresponding to a gear ratio, in an epicyclic gear system created by a main gear body, ball driver and gear holder with gears. The drive shaft contains keyed structures and, depending on its position within the gear system, the keyed structures on the drive shaft engage or disengage a plurality of key stops. The key stops, in turn, interact with the gears to generate the desired gear ratio. The contours of the keyed structures on the gear holder allow the drive shaft to move between positions without first being specifically positioned. The gear-driver adapter also includes a handle adapter and a driver adapter, allowing users to use any handle or driver with the gear-driver adapter.

Abstract: A powered threading machine is described. The threading machine is compact and portable. The threading machine includes a tube frame having a rearward wheel assembly and an extendable handle at the front of the machine. A particular sump configuration is used to prevent loss of cutting oil during operation and transport of the machine.

Abstract: A hand-held cutting tool may include a handle and a battery pack. The handle has a rear portion with respect to a work proceeding direction along which the cutting tool is moved for performing a cutting operation. When the battery pack is mounted to the rear portion of the handle, the longitudinal direction of the battery pack extends non-parallel with the work proceeding direction.

Abstract: A tapping tool is mountable on an adapter for tapping. The adapter includes a ring gear in which the tapping tool is mountable; and a gear holder in which the ring gear is disposed and which is mountable on a turret of a turret punch press so as to locate the disposed ring gear at a position corresponding to a punch mounting section formed in advance in the turret. The tapping tool includes a cylindrical body and a rotating body.

Abstract: A method for machining a through-hole in a wall of a component, includes setting in rotation on itself a cutting tool about a rotation axis and setting the rotation axis of the tool in rotation about a first orbital rotation axis parallel to, and eccentric by an eccentricity E with respect to, the rotation axis of the tool. The method further includes setting the first orbital rotation axis in rotation, over at least one revolution, about a second orbital rotation axis parallel to, and eccentric by an amount f with respect to, the first orbital rotation axis, the eccentricity being fixed. This configuration makes it possible to balance the elements located between the rotation axis of the tool and the first orbital rotation axis, so that the rotation axis can thus be set in rotation about the first orbital rotation axis at high rotational speeds that contribute toward increasing productivity.

Abstract: A method of in-situ pipeline replacement in which valves, fittings, and other obstructions are removed from an existing pipeline, a heat-fusible polymer pipeline having an initially deformed configuration less than the existing pipeline diameter is inserted into the remaining portions of the existing pipeline and reformed to substantially conform to the inside diameter of the existing pipeline, heat-fusible fittings are provided to replace removed portions of the existing pipeline and heat-fused to the polymer liner, and transition fittings provided to operably connect the replacement pipeline to those portions of the existing pipeline not within the replacement scope. The completed replacement polymer pipeline creates an operable wetted pressure boundary within the bounds of the replaced existing pipeline.

Abstract: Power supplied by a power tool is used to induce a magnetic field in a tool piece attached to the power tool. The magnetic field is produced by an electromagnet coil and can be used to hold items such as screws in position on a tool piece such as a driver bit.

Abstract: The present disclosure provides exemplary collapsible drills and associated methods of use. Thus, in one aspect, the disclosure provides a collapsible drill including or comprising a chuck, a piston and a motor section. The chuck can be configured and dimensioned to receive a drill bit. The piston can include a pair of interlocking splines. The motor section drives rotation of the piston and the chuck. Depression of the piston can stop rotation of the chuck relative to the piston. In another aspect, the disclosure provides methods of drilling into a material that include providing a collapsible drill, driving rotation of the piston and the chuck with the motor section, and depressing the piston to stop rotation of the chuck relative to the piston.

Abstract: In one embodiment of the present invention, a power tool includes a housing having a first opening formed therein with a motor being contained within the housing. The tool includes a device for sharpening a writing implement. The sharpening device is at least partially contained within the housing and accessible through the first opening which permits the writing implement to be inserted into the sharpening device. The sharpening device is operatively connected to the motor such that operation of the motor drives the sharpening device.

Abstract: A combination cutter and transmission shaft assembly used in a plastic pelletizing machine for cutting off an extruded plastic material from a perforated plate into plastic pellets is disclosed to include a transmission shaft rotatable on and axially movable along the axis thereof, and a cutter unit including a cylindrical cutter holder axially slidably coupled to and rotatable by the transmission shaft, a spring member mounted in the cylindrical cutter holder and stopped between one end of the transmission shaft and an inside wall of the cylindrical cutter holder and a plurality of cutter blades mounted at one end of the cylindrical cutter holder and kept in contact with the perforated plate and rotatable with the cylindrical cutter holder over the perforated plate.

Abstract: A tapping tool is mountable on an adapter for tapping. The adapter includes a ring gear in which the tapping tool is mountable; and a gear holder in which the ring gear is disposed and which is mountable on a turret of a turret punch press so as to locate the disposed ring gear at a position corresponding to a punch mounting section formed in advance in the turret. The tapping tool includes a cylindrical body and a rotating body.

Abstract: A boring device according to the present invention includes: a hollow main shaft; a table supporting the main shaft rotatably about a predetermined axis; a tool holder extending in the form of a bar and configured to rotate coaxially with the main shaft; a radially protruding tool provided at a distal end portion of the tool holder; a tilting unit provided between the main shaft and the tool holder in the axis direction and configured to cause the tool holder to be inclined from the axis; a drawbar configured to be movable back and forth in the axis direction within the main shaft; a first drive unit configured to rotate the main shaft about the axis; and a second drive unit configured to move the drawbar back and forth in the axis direction.

Abstract: The invention refers to a motor spindle for a machine tool which includes a tool clamping system configured to automatically clamp and release an adjustable tool, a control rod arranged within the tool clamping system, and a setting unit arranged at a B side of the motor spindle which is configured to adjust an adjustable tool via the control rod.

Abstract: The present invention is a coring unit adapted to be engaged to an articulated arm, to reduce the labor necessary for on-site coring of sewage and water pipes. The coring unit includes a frame containing the components of the unit, which include a coring bit, a coring bit motor, a traverse mechanism, and a stabilizer for allowing ready orientation of the coring unit with respect to an object being cored. The unit may also be provided with a traverse motor for driving the coring bit into an object being cored, and for withdrawing the coring bit once a core has been formed. The coring unit may additionally be adapted to allow for remote operation of the coring unit.

Abstract: A method for machining a through-hole in a wall of a component, includes setting in rotation on itself a cutting tool about a rotation axis and setting the rotation axis of the tool in rotation about a first orbital rotation axis parallel to, and eccentric by an eccentricity E with respect to, the rotation axis of the tool. The method further includes setting the first orbital rotation axis in rotation, over at least one revolution, about a second orbital rotation axis parallel to, and eccentric by an amount f with respect to, the first orbital rotation axis, the eccentricity being fixed. This configuration makes it possible to balance the elements located between the rotation axis of the tool and the first orbital rotation axis, so that the rotation axis can thus be set in rotation about the first orbital rotation axis at high rotational speeds that contribute toward increasing productivity.

Abstract: A power drill can comprise a housing having a motor that includes an output member. A rotary output spindle can be journaled in the housing. A transmission can be disposed in the housing and include a first output gear and a second output gear. The transmission can selectively couple the output member to the output spindle through one of the first output gear or the second output gear for rotating the output spindle at one of a first speed or a second speed, respectively. A speed shift assembly can include a guide plate and a user engageable member. The guide plate can selectively influence movement of the first and second output gears. The user engageable member can be movable between a first speed position and a second speed position. Movement between the first and second positions can cause the second output gear to at least partially nest into the first output gear.

Abstract: A power tool can utilize a handle that engages with a large portion of the housing and can distribute the stresses incurred by the handle over a larger area. The handle of the power tool can be a stick handle or a guard handle. The handle may be utilized to position sensors therein at positions that are remote from the working bit of the power tool. Accessory handles, such as a bail handle and a side handle, can be mounted to a single set of machined passages on the housing.

Abstract: Nonmetallic tools such as rotary bits, circular blades, and scything tools are described that may be suitable for removing cured flexibilized epoxy gap-filler materials from gaps between soft composite materials. The nonmetallic tools may be formed from various plastic or composite materials that are sufficiently hard to cut through the gap-filler material while being sufficiently soft to avoid damaging adjacent areas of soft composite materials. Methods for using the nonmetallic tools may include attaching the nonmetallic tools to a suitable machine-driven tool and contacting the nonmetallic tools to a material to be cut, shaped, or drilled.

Abstract: An auxiliary handle for a hand-held power tool has a handle piece, a fixation means for fixing the auxiliary handle to the hand-held power tool, a rod with at least one set of teeth, and a guide in which the rod is seated longitudinally movably. A locking mechanism has a pawl, a pivot axis about which the pawl can be rotated between a locking position and a release position, and at least one locking tooth on the pawl that engages in a locked position with the guide, and is pivoted out of the guide in a release position. A spring element initially tensions the pawl into the locking position. A distance of the spring element from the pivot axis is less than a distance of the locking tooth from the pivot axis.

Abstract: A servo drill spindle includes a spindle body, an air motor slidably carried by the spindle body, a spindle extension drivingly engaged by the air motor, a cutting tool drivingly engaged by the spindle extension and a servo motor engaging the air motor and operable to advance the air motor along the spindle body.

Abstract: A drill press includes a housing and a motor assembly, with a motor carriage attached to the housing. The motor assembly includes an electric motor and drill bit, and the motor carriage is operable for moving the motor assembly relative to the housing. A base, coupled to a portion of the housing, is operable for magnetically coupling the tool to a workpiece. The drill press also includes a DC power source and an AC power input for providing power to the motor. A power supply switching unit, electrically coupled to DC power source and the AC power input, selectively electrically couples the motor with one of the DC power source and the AC power input for providing power to the motor.

Abstract: An apparatus for a drilling operation. In one advantageous embodiment, the drilling operation includes a motor, a rotary sensor, and a controller connected to the rotary sensor. The rotary sensor may be capable of generating a signal in response to rotary movement of the drill motor. The controller may be capable of monitoring a speed of the air motor from the signal generated by the rotary sensor and may be capable of identifying a change from a current layer in a stackup to a new layer in the stackup using the signal.

Abstract: The invention discloses a drilling machine, in particular a hand-held core drilling machine, having a drive with a motor that can be coupled to a tool spindle in order to drive the latter, wherein the drive allows at least a first transmission stage and a second transmission stage, having a center mount for mounting a pilot drill and having a tool mount for mounting a drill bit, wherein the drill bit and the pilot drill can be mounted substantially concentrically with one another, wherein the pilot drill, in particular in order to drill a pilot hole, can be driven in a first rotational speed range by means of the first transmission stage and wherein the drill bit, in particular in order to drill a core hole, can be driven in a second rotational speed range by means of the second transmission stage.

Abstract: An improved pneumatic ADE-machine with a built-in logic has a clutch in the power transmission chain between a first drive gear and a second driven gear. The clutch includes two clutch parts (D, F), whereof a first part (D) is axially biased by a spring (C). Movable elements (E) are arranged between the clutch parts, which transfer the rotation from the first to the second clutch part, and an actuator (H) is arranged in connection with the first spring biased clutch part (D). When a feed force on a drill during drilling exceeds the biasing force of the spring, the movable elements displace the spring biased clutch part axially, which triggers the actuator (H) to send a corresponding signal to the machine logic.

Abstract: A chuck, adapted to secure a power tool bit to a power tool, includes an output operably coupled to a motor to receive torque from the motor. The output at least partially supports therein the power tool bit. The chuck also includes an outer body having a cavity and rotatable relative to the output, and a lever coupled to the outer body and movable between a first position, in which the lever is at least partially retracted into the cavity, and a second position, in which the lever is extended from the cavity.

Abstract: The present invention is a coring unit adapted to be engaged to an articulated arm, to reduce the labor necessary for on-site coring of sewage and water pipes. The coring unit includes a frame containing the components of the unit, which include a coring bit, a coring bit motor, a traverse mechanism, and a stabilizer for allowing ready orientation of the coring unit with respect to an object being cored. The unit may also he provided with a traverse motor for driving the coring bit into an object being cored, and for withdrawing the coring bit once a core has been formed. The coring unit may additionally be adapted to allow for remote operation of the coring unit.

Abstract: A power drill can comprise a housing having a motor that includes an output member. A rotary output spindle can be journaled in the housing. A transmission can be disposed in the housing and include a first output gear and a second output gear. The transmission can selectively couple the output member to the output spindle through one of the first output gear or the second output gear for rotating the output spindle at one of a first speed or a second speed, respectively. A speed shift assembly can include a guide plate and a user engageable member. The guide plate can selectively influence movement of the first and second output gears. The user engageable member can be movable between a first speed position and a second speed position. Movement between the first and second positions can cause the second output gear to at least partially nest into the first output gear.

Abstract: A chuck assembly configured to provide a shorter longitudinal profile. The chuck assembly includes a chuck body with a support bearing mounted to a rear portion of the chuck body and mounted to a portion of a housing such that a cavity is defined axially rearward of the support bearing and is configured to receive the jaws when the rear portion of the jaws extend axially rearward. The chuck assembly can be incorporated into a tool driven by a motor. In some aspects, the tool may include a speed change mechanism, a torque adjustment mechanism, or both.

Abstract: A chuck assembly configured to provide a shorter longitudinal profile. The chuck assembly includes a chuck body with a support bearing mounted to a rear portion of the chuck body and mounted to a portion of a housing such that a cavity is defined axially rearward of the support bearing and is configured to receive the jaws when the rear portion of the jaws extend axially rearward.

Abstract: A drilling unit with automatic drill shaft feeding is provided. The feeding velocity can be changed by external mounting of exchangeable gearing cassettes having a desired gear ratio.

Abstract: A locking assembly for the spindle of a tool includes a locking member, a biasing member interconnected with the locking member, and a collar surrounding a portion of the spindle. The spindle includes a spindle slot that receives the locking member to lock the spindle with respect to the tool housing. The collar may be rotated into an unlocked position in which the biasing member holds the locking member out of engagement with the spindle slot. The collar may also be rotated into a locked position in which a cam surface in the collar acts on the biasing member to apply a biasing force on the locking member toward engagement with the spindle slot. The biasing member may deflect to accommodate rotation of the collar into the locked position with the spindle slot not aligned with the locking member.

Abstract: A tool (10) including a drive shaft (36) having an axis of rotation, and a plurality of bit holders (28,30) interchangeable with one another at a position of use. The bit holders (28,30) being mounted on a turret (26) which is rotatable around an axis (k) set at an angle to the axis of rotation of the drive shaft (36). The drive shaft (36) being in drive connection with a respective bit holder (28,30) at the position of use, wherein the tool (10) includes means (20x) for engaging a clutch (46) which activates a drive train (44) to establish a drive connection between the drive shaft (36) and the turret (26) so that subsequent operation of the drive shaft (36) rotates the turret (26) to interchange the positions of the bit holders (28,30) at the position of use, and wherein after the turret (26) has been rotated the clutch (46) is disengaged to deactivate the drive train (44) to prevent any further rotation of the turret (26).

Abstract: A spindle attachment device attached, for use, to a distal end of a spindle of a machine tool is provided. The spindle attachment device (11) includes a hollow casing (13) having an internal space; an input shaft (17) rotatably supported inside the casing; an output shaft (19) rotatably supported inside the casing; a coupling member (15) connected to the input shaft in order to join the input shaft to the spindle of the machine tool; a gear train (21) disposed between the input shaft and the output shaft in order to increase a rotation speed of the input shaft for a transmission to the output shaft; and a tap holder (25, 27) for mounting a tapping tool on the output shaft. The spindle attachment device increases the rotation speed of the spindle and transfers it to the tapping tool, and thus makes it possible to perform a tapping process on a workpiece at high speed, while maintaining the rotation speed of the spindle at a low level.

Abstract: The present invention discloses a one-way clutch capable of eliminating the phenomenon of “teeth scraping”, comprising: ratchet member, pawl seat, pawl member, control outer sleeve and control member provided with control portion, wherein at least one of the control portion or the pawl member has a first slope capable of being in contact with the other one of the control portion or the pawl member and said pawl member exerts a force towards the second direction on the control portion.

Abstract: An adapter (21) for tapping used in a turret punch press, comprises: a ring gear (29) in which a tapping tool (25) is mountable; and a gear holder (31) in which the ring gear is disposed and which is mountable on a turret (9) of the turret pinch press so as to locate the disposed ring gear (29) at a position corresponding to a punch mounting section (33) formed in advance in the turret (9) of the turret punch press.

Abstract: A tapping tool having a guide body, a driver for longitudinal movement of a tap within the guide body, and a pump for lubricating the tap. A keyway in the outer body of guide body mates with an indexing key in a rotatable indexing holder of a turret press, which causes the guide body to rotate in sync with the turret press. A driver cylinder is centrally disposed in the guide body. The driver is adapted for sliding, mating engagement within the driver cylinder. A chamber in the lubrication pump holds the lubrication which is ejected by the pump onto the tap. Lubrication is ejected onto the tap through a normally closed ejector inlet that is opened by downward movement of a plunge pin against the lubrication in the chamber. The ejector is sized to restrict the flow of lubrication from the ejector outlet, which creates back pressure in the lubrication chamber. The back pressure forces a ball to close the lubrication conduit when the plunge pin moves downward.

Abstract: A main shaft locking mechanism includes a fixing ring, a main shaft and detents. The main shaft includes an equilateral portion that has an equilateral cross section. A number of the corners of the equilateral portion is equal to that of the detents. The detent has an exterior side and an interior side opposite to the exterior side. The interior side includes two corner protrusions protruded out from two ends thereof and a concave portion defined between the two corner protrusions. The corners of the main shaft are received in the concave portions of the detents. When the main shaft is manually driven to rotate, the corners of the main shaft drive the detents to deviate. Therefore, the exterior sides of the detents interfere against the fixing ring. Then the detents prevent the main shaft from further rotating, thus locking up the main shaft.