40 results about "Dead centre" patented technology

The utility model relates to the technical field of bipolar plate press machines, in particular to a dynamic error control and compensation mechanism of a bipolar plate press machine, which comprises a main servo motor direct drive transmission gear shaft and a driven eccentric gear, a connecting rod mechanism adopts a toggle rod type structure and comprises a connecting rod, a corner bracket and a lower connecting rod, and the lower connecting rod is connected with a sliding block adjusting screw rod. A sliding block adjusting servo motor drives a worm and a worm gear transmission mechanism, an adjusting nut structure is arranged in a worm gear and forms a connecting pair with an adjusting screw rod, the worm gear rotates to drive the sliding block adjusting screw rod to move up and down so as to adjust the die height of the sliding block, and the sliding block is provided with an inductance type linear displacement sensor. The main servo motor and the sliding block adjusting servo motor are connected with the displacement sensor through the PLC, the mold closing speed and the mold closing position of the mold are monitored and accurately controlled in real time, high-precision adjustment of mold closing of the mold is achieved, and the position of a bottom dead center can be accurately controlled and compensated in real time.

A low-pressure module suitable for large-capacity flow air turbine relates to the field of compressed air energy storage. The invention comprises a low-pressure outer cylinder, a low-pressure inner cylinder, a bearing box, a gas seal assembly and a corrugated joint. The inner and outer cylinders adopt a horizontal middle-embedded structure and are centered by three sets of adjusting shims. The low-pressure outer cylinder and the inner cylinder are provided with symmetric tangential double air inlets, cooperate with the bottom exhaust structure, and the size of a single air inlet is controllable, the flow field is uniform, and the pressure loss is small. The inner and outer cylinders are flexibly connected by the corrugated joint to absorb the thermal expansion difference; the outer cylinder is supported by the gravity of the base frame and provided with an anchor plate to form an expansion dead point. The inner cylinder adopts an integrated cast flow guide ring, the volute is provided with a flow guide rib plate, and the module adopts 4-stage thrust self-balancing blades. The invention solves the problems of large cylinder, poor sealing strength, and unstable shaft system caused by single air inlet under super large flow, has the advantages of high aerodynamic efficiency, good strength and rigidity, stable operation, and low cost, and is suitable for 350MW-660MW air turbine.

An engaging device of a Mass-Interconnect includes an interchangeable test adapter (ITA) and a locking mechanism. The locking mechanism includes a slide movable between an engaged position and a disengaged position, a dual cam including a first cam arm and a second cam arm respectively configured to contact a first slide leg and a second slide leg to drive the slide between the engaged and disengaged positions, and plurality of contact pads disposed on the slide at regions engaged by the dual cam, the contact pads being made of a resilient polymeric material. The contact pads provide elastic compressibility that enables the receiver and ITA to achieve a substantially zero-gap condition at their mating surfaces while the locking mechanism advances into an over-dead-center locked state.

The present invention relates to an alternative two-stroke reciprocating internal combustion engine and power system thereof which eliminates the intake and compression phases of four-stroke Otto engines, and injects the fuel and the oxidising agent at high pressure directly into the combustion chamber or a prechamber at approximately the moment when the piston is at the top dead centre (TDC), using oxygen and / or air as the oxidising agent and hydrogen-based fuels, synthetic fuels, biofuels, alcohols, natural gas and mixtures thereof. At the same time, a spark is applied or combustion is produced by self-ignition, and expansion occurs until the piston reaches the bottom dead centre (BDC). The piston then starts to rise, the mechanically or electrically actuated exhaust valve opens and exhaust is discharged until the TDC is reached again, thereby repeating the cycle.

The invention relates to a sensitive and self-adjusting detection system for inter-row hoes that comprises a motor (1) with a shaft (2), a sensing rod (3) joined to the shaft (2), and a sensor (5) that determines at least one of the following parameters: speed, rotation, angular position or torque of the shaft (2). The system also includes a control element (10) for varying the position of the sensing rod (3), and a control unit (6) that receives signals from the sensor (5), from the control element (10) and, optionally, from other sensors (8, 9). The control unit (6) processes the signals and allows automatic regulation of the position, sensitivity and dead centre of the sensing rod (3), improving weeding precision and adapting operation to the working conditions of the terrain.

The utility model belongs to the technical field of instruments and meters, and relates to a pneumatic motor actuating mechanism which comprises a box body, a driving gear set and a transmission output assembly are rotatably arranged in the box body, and the driving gear set can drive the transmission output assembly. The box body is provided with a pneumatic module and a manual assembly in a matched mode, and the pneumatic module and the manual assembly can respectively drive the driving gear set to rotate. A manual and automatic clutch is arranged on a box cover of the box body and can adjust the axial position of a first-stage driven bevel gear of the driving gear set so that a first driven bevel gear constructed at the upper end of the first-stage driven bevel gear can be meshed with a first-stage driving bevel gear connected with the output end of the pneumatic module. The actuating mechanism is simple and reasonable in structure, safe and reliable to operate and capable of improving undesirable phenomena such as unsmooth action or action dead points; clutch switching is achieved through the manual and automatic clutch, and automatic operation and manual operation do not affect each other.

A transmission for a human-powered vehicle. The transmission has a primary system that includes a transmission case, a crankshaft with cog, a pair of receiver cranks, a pair of connecting rods, a pair of oscillating driver cranks, and a pair of pedals. A secondary biasing system is engaged with the primary system to provide a favorable torque around dead centers of the primary system. The transmission 150 may be configured to transmit power by driveshaft, chain, or belt to drive a wheel or propeller. In a watercraft application, an operator alternatingly applies force to a pair of pedals while seated close to the floor of a kayak 145. Power from the transmission is transmitted through a steerable lower gear case 134 via a propeller to propel the craft. The operator maneuvers the craft by means of a control lever 135 operably connected to the lower gear case by cables 136.

The invention relates to a method of combusting a first liquid fuel and a second liquid fuel in an internal combustion piston engine, the first liquid fuel having a lower heating value than the second liquid fuel, wherein - a first liquid fuel is injected into a cylinder of the engine as a main fuel, which brings most of the energy into the process, so that the total amount of first liquid fuel delivered to the cylinder for one combustion stage is divided into at least two partial injections, wherein - the main injection of the first liquid fuel accounts for 70-95% of the total amount of the first liquid fuel, and - the start of the main injection occurs at the latest at 20°CA before the top dead centre position of the piston in the cylinder, - the pre-injection of the first liquid fuel accounts for 5-30% of the total amount of the first liquid fuel, and wherein - the start of the pre-injection occurs at 20-55°CA before the top dead centre position of the piston in the cylinder, and the pre-injection is formed by one injection event, and - a second liquid fuel is injected into the cylinder of the engine as a fuel assisting compression ignition, so that the start of the injection of the second liquid fuel occurs at 1-23°CA before the start of the injection of the main injection of the first liquid fuel.

The utility model discloses a stacked type balance valve which can prevent a double-acting executing element (such as a hydraulic oil cylinder and a hydraulic motor) from moving in an accelerated mode or moving out of control in the load direction when the double-acting executing element is provided with a suspended, pulled or moving load, namely the speed is not consistent with the input oil quantity (pump) (the oil cylinder is broken due to air suction). The load directions of the lifting equipment and the swinging equipment change positively and negatively; the swinging equipment swings over a dead point; as a side effect, when a reversing valve or a direction slide valve control loop leaks at a balance position, an oil cylinder piston can be prevented from accidentally disallowed displacement (two-way pressure maintaining) in the load direction. According to the utility model, the stacked intelligent module is designed, which is very convenient to overhaul, install and process problems. According to the utility model, the two sandwich valves can be quickly disassembled and assembled by adopting the mounting component and the connecting rod, so that the earlier-stage mounting, free combination and subsequent disassembly and maintenance are greatly facilitated.

The utility model relates to the technical field of belts, and provides an eccentric counterweight type high-strength belt dynamic tension balancing device which comprises a rectangular plate, an adjusting rod fixedly installed at the other end of a first spiral spring, a second spiral spring fixedly installed at the other end of the first spiral spring, and a third spiral spring fixedly installed at the other end of the second spiral spring. The adjusting rod is movably embedded in the cylindrical groove; the U-shaped plate is fixedly mounted at the top of the adjusting rod, and a positioning wheel is movably embedded in the U-shaped plate; the two electric push rods are started at the same time, the two sets of positioning rods are pushed to slide in the through holes through the connecting plates, the positioning rods drive the annular plates to slide on the outer surfaces of the positioning wheels through the connecting blocks, the two annular plates move oppositely or oppositely under the action of the electric push rods, adjustment is conducted according to the size of the belt, and the belt is positioned. The belt is prevented from sliding left and right on the outer surface of the positioning wheel, friction of the belt is reduced, and the service life of the belt is prolonged.

The present invention relates to an operating mechanism for a switchgear, comprising: a rotatable output shaft (11) configured to perform a circuit breaking or closing operation of the switchgear by rotation; a rotatable energy storage rod (13) and a spring (4), wherein the energy storage rod (13) is configured to rotate by a motor (1) to drive the spring (4) to be compressed to store energy; and a rotatable drive rod (12) connected to the output shaft (11), rotatably connected to the energy storage rod (13) and freely rotatably connected to the spring (4) to allow ≤60° rotatability between the drive rod (12) and the spring (4) for performing a circuit breaking or closing operation of the switchgear, wherein the spring (4) is configured to release energy during at least one period of the circuit breaking and closing operation of the switchgear to rotate the drive rod (12) after passing through the dead position of the spring (4).

The invention discloses an electric switch driven by a motor, which at least comprises an insulating shell, and a moving contact assembly, a static contact assembly, a motor and a gear assembly which are arranged in the insulating shell, the gear assembly is at least composed of two groups of gears and a turntable, and a fan gear is provided with at least one driving end; the rotating disc is provided with a force bearing end corresponding to the driving end, a reset elastic piece is arranged between two sets of end faces, matched with the rotating disc, of the sector gear, the reset elastic pieces are used for driving the sector gear to rotate and are meshed with the cylindrical gear or the turbine, an idle running angle of at least 20 degrees is arranged between the driving end and the force bearing end, and after the contact passes a dead point in the opening process, the contact is driven to rotate. When the counter-force elastic piece releases energy, the idle running angle of one side of the driving end and one side of the stress end is reduced, the counter-force elastic piece releases energy to drive the moving contact assembly to be quickly bounced off, and the effect that the moving contact assembly and the static contact assembly are quickly opened is achieved. Therefore, rapid arc extinguishing is realized, the electric service life is prolonged, the large-current breaking capacity is improved, and the safety and reliability of products are improved.

The invention relates to a combustion engine comprising cylinders (2) arranged in parallel in a circle around a rotary output shaft (3) and provided with fuel injectors (5), spark plugs (6), gas outlets (7) and pistons attached to longitudinally movable piston arms (8). The piston arms (8) comprise a freewheel (9) on which a gear (10) is mounted, the gear being provided with a series of free-rotation rollers (11) that make contact with helical tracks (20) of a rotor (19) that is solidly connected to the output shaft (3), rotating same. The output shaft (3) comprises a helical ramp section (21) which, during operation of the combustion engine, acts sequentially on the successive piston arms (8), moving same towards top dead centre in a compression cycle or time.

The utility model discloses a foldable supporting leg and an overhead working truck, and belongs to the technical field of overhead working trucks. The supporting leg comprises a first hydraulic cylinder, one end of the first hydraulic cylinder is connected with a transverse leg main arm, and the other end is connected with a transverse leg telescopic arm. The transverse leg telescopic arm is nested in the transverse leg main arm and can slide in the transverse leg main arm; the transverse leg telescopic arm is hinged with the vertical leg; the transverse leg telescopic arm is hinged to a first dead point rod, the vertical leg is hinged to a second dead point rod, and the first dead point rod is hinged to the second dead point rod; the other end of the second hydraulic cylinder is hinged with the first dead point rod; the transverse leg main arm is arranged on the carrying mechanism; when the supporting leg is in a folded state, the first dead point rod and the second hydraulic cylinder are contracted in the hollow structure in the transverse leg telescopic arm, the second dead point rod is contracted in the hollow structure in the vertical leg, and the vertical leg and the transverse leg telescopic arm are jointly contracted in the transverse leg main arm. The dead point structure and the reinforcing ribs are adopted, so that materials and cost are saved, and the overall stability is improved.

The invention relates to the technical field of casting equipment, in particular to precoated sand shell mold casting equipment. The invention provides precoated sand shell mold casting equipment which comprises a base, rolling wheels which are evenly distributed are rotatably connected to the base in the horizontal direction and used for bearing and conveying a lower mold, guide frames which are symmetrically distributed are fixedly connected to the base, and first sliding blocks are slidably connected to the interiors of the guide frames in the vertical direction; an upper die is connected between the symmetrically-distributed first sliding blocks in a horizontal sliding mode, and a support is fixedly connected to the base. The toggle rod linkage mechanism is driven by the cam, so that stable lifting of the upper mold is realized; during mold closing, through rapid approaching and low-speed high-pressure reinforcement, idle stroke is shortened, mold locking force is amplified, and sand shooting leakage is prevented; mold opening is slowly relieved from a dead point, and a shell mold or a mold is prevented from being damaged; the toggle rod is mechanically self-locked after going through the dead point, the motor stops rotating, the mold is still closed, safety and stability are improved, energy consumption is reduced, and the problems that mold opening and closing of traditional equipment are prone to being stuck, and stability is poor are fundamentally solved.

The utility model discloses a fan power control device, and relates to the technical field of power transmission control. The device is used for controlling separation and combination of a clutch and comprises a support, and a separation action structure used for pushing a separation bearing of the clutch is installed on the support. An operating rod is installed on the support in a swinging mode, the operating rod is connected with a wire pulling structure used for pulling the separation action structure, and the separation action structure is connected with a reverse pulling force application structure; the operating rod is locked after the rod side connecting point of the stay wire structure crosses a dead point in the separation swing direction, and a locking position limiting structure is arranged on the support. The power separation and locking device not only realizes power separation and locking, but also facilitates power recombination, and is simple in structure and reliable in use.

There is provided a cutting blade drive apparatus including: cutting blade units including a plurality of cutting blades arranged on a flat surface; a base unit configured to support the cutting blade units overlapping one another; and a drive mechanism supported by the base unit and configured to drive at least one of the cutting blade units to perform cutting operation. The plurality of cutting blades protrude from a circumference of the base unit in different directions. The drive mechanism allows at least one of the cutting blade units to translate drawing a circular orbit with no dead center so that the cutting blades of one cutting blade unit and the cutting blades of another cutting blade unit overlap to perform the cutting operation.

The utility model provides a motorcycle which comprises a motorcycle frame, a motorcycle body covering part, a walking system and a support, the support comprises a support installation part, a side support and an extension spring, the side support rotates with the support installation part as the axis so as to be switched between a parking position and a folding position, and the extension spring is connected between the side support and the support installation part. The extension spring is provided with a spring dead point position, and the spring dead point position is located between 60 degrees and 70 degrees of rotation from the folding position to the parking position. Therefore, in the parking process, the dead point position of the spring is located in the stroke range of thrust applied to the side support by a driver and passengers, the side support cannot stop at a certain position between the dead point position and the folding position A due to lack of the elastic force of the spring after passing through the dead point position of the spring, and then the driver and passengers can stop at a certain position between the dead point position and the folding position A in the parking process. The side support can be pushed and pulled from the folding position A to the parking position B more easily, and the use feeling of a driver and passengers can be improved.

A sliding pin system of a 100 MW photothermal steam turbine, relating to the fields of electric power, etc. The present invention aims to solve the problem of rotor-stator rub impact caused by the lifting of medium-pressure cylinders during the expansion of sliding pin systems in existing integrated wind-photovoltaic power stations. In the present invention, a steam turbine high-pressure cylinder (1) is connected to a front bearing box (3) by means of a front bearing box vertical key (5), and is connected to a middle bearing box (4) by means of a high-pressure cylinder centering beam (6); when a unit is in a hot state, the steam turbine high-pressure cylinder (1) expands in the direction towards the front bearing box (3) with the middle bearing box (4) as a dead point; a medium-low-pressure cylinder (2) is connected to the middle bearing box (4) by means of a middle box claw transverse key (9) and a middle box vertical key (7), and expands towards a steam discharge side with the middle box claw transverse key (9) as a dead point. During the rapid start process of the unit, the expansion is smooth, and the sliding pin system is not stuck, thus satisfying the cold start time of photothermal steam turbines. The present invention is used in steam turbines.

The application relates to a motor, in particular to the technical field of a synchronous motor with a permanent magnet, and discloses an axial flux permanent magnet synchronous motor which comprises a motor shell and an output shaft, a stator assembly is arranged in the motor shell, a rotor assembly is connected to the output shaft, the rotor assembly is arranged in the motor shell, a centrifugal assembly is arranged on the rotor assembly, the stator assembly comprises a stator ring, the stator ring is fixedly connected to the inner wall of the motor shell, through linkage cooperation of the stator ring, a winding slot, an arc-shaped plate and a permanent magnet one, instantaneous thrust is generated by the arc-shaped plate protruding end contacting the permanent magnet one, torque loss of a magnetic resistance dead point in the rotation process of the rotor is compensated, the problem that the rotor is fixedly easy to appear at a fixed point and the angle is rotated back in the existing axial flux permanent magnet synchronous motor is solved, and the structure limitation that the stator and rotor magnetic circuits cannot be adjusted in the prior art is different, and effective improvement of rotation smoothness in the low-speed rotation process of the rotor is realized.

The invention discloses a double-side dead point self-locking transmission mechanism of a high-voltage sulfur hexafluoride double-acting circuit breaker, which is characterized in that a first connecting rod is hinged with a first linear motion piece, a second connecting rod is hinged with a second linear motion piece, the axes of the first linear motion piece and the second linear motion piece coincide, and the first linear motion piece and the second linear motion piece do linear motion in the same direction or opposite directions; the first rigid connector is formed by rigidly connecting a first crank and a first rocker at an included angle, the second rigid connector is formed by rigidly connecting a second crank and a second rocker at an included angle, and the fixed ends of the first crank and the second crank are respectively connected with the arc extinguish chamber fixing rack through a first rotating shaft and a second rotating shaft; according to the self-locking transmission mechanism, when the circuit breaker is in an opening position, the first rocker and the first connecting rod are collinear, the second rocker and the second connecting rod are collinear, and a double-side mechanism synchronously enters a dead point self-locking state, so that accurate synchronization of double-side transmission and reliable self-locking of the opening position are realized, and the breaking performance and the operation reliability of the high-voltage circuit breaker are comprehensively improved.

The utility model discloses a novel electric remote control unhooker, including hook body, hanging claw installation slot, butt joint axle, claw and remote control drive mechanism, and the hanging claw installation slot sets at the bottom center place of hook body, and the butt joint axle rotation is connected in the hanging claw installation slot. In the utility model through electric control hydraulic push rod drive driving link, and then through lever structure drive first linkage link, second linkage link whole linkage, make abutment block promote two adjacent claw relative rotation, until its both one end mutual abutment, and at this time driving link and linkage link between combination constitute lever dead point, and cooperate strong magnet and firmly adsorb the connecting place, avoid needing electric control hydraulic push rod and continuously exert force, compared with traditional motor drive mode, electric control hydraulic push rod can output greater force, this makes the claw when clamping material can obtain far more than motor drive's clamping force, ensures that material is firmly locked in the hoisting process.

The present application relates to the technical field of hydraulic motor assembly equipment, and specifically discloses a conveying device for hydraulic motor assembly, which comprises a rack, a conveying mechanism and a travelling assembly carrier, the travelling assembly carrier is provided with a carrier base, the carrier base is provided with a posture switching assembly and a over-center unloading locking assembly, and the rack is provided with a station triggering assembly at an assembly station; the posture switching assembly is provided with a turnover bearing, and the turnover bearing is provided with a holding positioning piece; the over-center unloading locking assembly is provided with a locking disc, a locking wedge and an unloading support rod; and the station triggering assembly is used for driving the locking wedge to be unlocked first, and then driving the turnover bearing to swing, after the turnover bearing swings to an inclined assembly posture, the locking wedge relocks the locking disc, and the unloading support rod passes the dead point and abuts against the carrier base. The device can complete assembly orientation switching during the line conveying of the hydraulic motor, and can transfer the assembly load to the carrier base during heavy load assembly, thereby improving the posture stability.

An internal combustion engine, system includes an internal combustion engine for combustion of gaseous fuel and having a combustion chamber at least partially delimited by a cylinder; a reciprocating piston moveable within said cylinder between a bottom dead centre (BDC) and a top dead centre (TDC), The reciprocating piston has a piston top end comprising a piston bowl intended to form part of the combustion chamber. A controllable fuel injector is arranged to inject gaseous fuel into the combustion chamber and towards the piston bowl. A controller controls the fuel injector to inject at least one gaseous fuel jet toward a bottom surface of the piston bowl during a fuel injection period occurring prior to an ignition event of the gaseous fuel.

This invention discloses a cavity ball assembly device and method, belonging to the field of valve parts assembly tooling technology, specifically involving precision assembly tooling for balls of various valves such as ball valves and regulating valves. The device includes a base, positioning and limiting components, a guide component, a push rod component, a drive component, a dual elastic component, a linear guide rail component, and a stroke limiting component. Through the coordinated operation of pre-pressure spacing and pressure-stabilizing reset dual springs, it achieves flexible press-fitting throughout the entire process, preventing drop, preventing part damage, and automatic reset. A dual-slider common rail motion reference plus a central floating ball guide plate compensates for coaxiality deviations, ensuring stable assembly accuracy. The hinged layout near the transmission dead point enables internal closed-loop self-balancing of the press-fitting force, allowing for stable single-handed operation without additional fixing fixtures. This invention has a compact structure, can be specifically adapted to different specifications of workpieces, and is suitable for small-batch continuous production of small-to-medium-sized interference fit balls in valves, as well as new product R&D and trial production scenarios, meeting the flexible production needs of small and medium-sized valve enterprises.

The aluminum clamp comprises a first C-shaped clamp and a second C-shaped clamp, one end of the first C-shaped clamp and one end of the second C-shaped clamp are mutually hinged, a handle is hinged to the end, away from the hinged end, of the first C-shaped clamp, and a locking positioning groove is formed in the face, back to the first C-shaped clamp, of the end, away from the hinged end, of the second C-shaped clamp. The opening direction of the locking positioning groove is the same as that of notches of the first C-shaped clamp and the second C-shaped clamp; the device further comprises a force storage spring, the force storage spring comprises a positioning section matched with the locking positioning groove and a locking section matched with the hinge hole, and the two ends of the positioning section are provided with first pull rod sections which are bent and then extend in the direction of the center of the groove opening of the first C-shaped clamp and the center of the groove opening of the second C-shaped clamp. When the handle is close to the outer side wall of the first C-shaped clamp along the hinge point, the handle, the hinge hole and the locking positioning groove pass through a dead point position formed by three points and one line to reach a locking state. The utility model has the advantages of low production cost, convenient installation, compact structure and reliable fixation.

The anti-rebound operating mechanism comprises a main shaft rotatably arranged on a side plate, the main shaft is used for being connected with a movable contact and being rotatable between a closed position and an open position, and the anti-rebound operating mechanism further comprises a rotatably arranged blocking piece, the main shaft is provided with a stop piece rotating with the main shaft, the blocking piece is provided with at least one blocking part and at least one avoiding part, the stop piece is provided with a striking structure and a pushing structure, when the main shaft rotates from the closed position to the open position, the pushing structure of the stop piece pushes the blocking piece to rotate so that the blocking part rotates to an anti-rebound position, when the blocking part is in the anti-rebound position, the blocking part is located on a rotating path of the striking structure when the main shaft rotates from the open position to the closed position, and the blocking part is located between the rotating center of the blocking piece and the striking structure, when the main shaft rebounds in the open position, the striking structure abuts against the blocking part to form a dead point to prevent the main shaft from rebounding, and the inertia is not needed to prevent the main shaft from rebounding.

The application relates to a method and system for controlling the precision of the lower dead point of a slider of an eddy current test press, and a medium, and relates to the technical field of lower dead point position monitoring. The method comprises the following steps: according to a preset press operation mode, the slider is controlled to move to a lower end position, which is marked as a lower dead point position; according to preset cam parameters, a data acquisition window is formed by determining a starting angle and a stopping angle of acquisition; according to the lower dead point position and an eddy current sensing position, an eddy current sensing interval is calculated; according to the eddy current sensing interval, the data acquisition window is triggered in combination with the rotating speed of a press main shaft to acquire an eddy current signal; the eddy current signal is converted and analyzed, the precision of the lower dead point is evaluated in combination with a preset precision threshold; invalid motion interval data is effectively removed through cam angle triggered data acquisition, and the signal-to-noise ratio is improved; mechanical wear is avoided through non-contact measurement of an eddy current sensor, the service life of equipment is prolonged, and the feedback time of lower dead point precision deviation is shortened.