Abstract: A rope socket comprises a slip cone subassembly having a straight outer diameter and a tapered inner diameter. A plurality of slips is positioned within the slip cone body. A retainer ring holds the slips together. A guide plug is positioned within the slips to maintain the slips in an opening position during insertion of a cable. A spring stabilizer having a spring thereon is coupled above the slip cone assembly to ensure even compression of the spring. A safety slot is located on the body of the rope socket in order to provide a visual indication of the cable position.

Abstract: A ball valve comprises a housing, a first seat surface, a second seat surface, and a ball rotatably movable within the housing. The ball contacts at least one of the first seat surface and the second seat surface to form a seal within the ball valve. The first seat surface and the second seat surface are fixed relative to each other, and pressure acting in a first direction and in a second direction opposite the first direction increases the contact pressure of the first seat surface and the second seat surface with the ball.

Abstract: A swellable packer for use in a subterranean well can include a seal element with a swellable material which contracts in response to temperature decrease, and a temperature compensator which applies increased force to the seal element in response to temperature decrease. A method of compensating for thermal contraction of a swellable material in a subterranean well can include a temperature of the swellable material increasing in response to installing the swellable material in the well, and a temperature compensator applying an increased force in response to a temperature decrease occurring after the temperature increasing step. A well tool for use in a subterranean well can include a swellable material and a temperature compensator which applies an increased force when the swellable material contracts.

Abstract: Methods and systems relate to recovering petroleum products from an underground reservoir. Injection of steam along with carbon dioxide into the reservoir facilitates the recovering, which is further influenced by operating pressure for the injection. Absorption of the carbon dioxide by the products and heat transfer from the steam to the products act to reduce viscosity of the products in order to aid flowing of the products.

Abstract: A fire suppression cylinder includes a valve at an outlet of a canister, and a control for the valve. The canister receives a liquid suppressor agent and a pressurized gas. A feature within a portion of the canister will receive the liquid suppressor agent. The feature increases the formation of gas bubbles within the liquid suppressor agent.

Abstract: A combined plug and sealing ring for a sprinkler nozzle includes a nozzle plug having a substantially cylindrical portion adapted to engage within a nozzle orifice of a sprinkler nozzle, and a cap overlaying the substantially cylindrical portion. A sealing ring is adapted to seat onto a threaded pipe fitting portion of the sprinkler nozzle. A leash interconnects the nozzle plug and the sealing ring. A combined plug and sealing ring in combination with a sprinkler nozzle, and a method of installing a sprinkler nozzle in a highly corrosive or extremely corrosive environment are also disclosed.

Abstract: Disclosed is an intelligent, autonomously usable closure for misting nozzles, atomizing nozzles and sprinklers. A covering plate 20 is fixed on the closure having a heat tripping device, a nozzle body 2, outlet channel 11 and outlet opening 10 by means of a melt tripping device 5. The melt tripping device 5 is activated when necessary by a heat element 23 and the outlet opening 10 is released. A structural element 21, such as a disk spring, ensures at the melting moment of the melt tripping device 5 that a force F is applied and the covering plate 20 is separated with force from the outlet opening. In case of emergency, the release is triggered without energy. The proposed autonomous device can be used in a system network and can also be integrated into an existing system.

Abstract: A self-contained automatic fire extinguishing device that is located within a wall or ceiling and housed within the space between two studs or joists. This unit includes a tank or series of tanks attached via flexible pressurized joints, and held in place by an expanding bracket. This fire extinguisher maintains a constantly high pressure inside a shell of the fire extinguisher through out a shelf-life of the fire extinguisher and which can indicate the charge status of the tank via a visible indicator. A sensor is attached to the unit, which reacts to prolonged exposure to direct heat and which can extend a nozzle beyond the wall or ceiling into the living space when actuated. The self-contained automatic fire extinguishing device is hidden behind a decorative face plate which permits the passage of the sensing device and a tank fill status indicator and which actuates out of the path of the nozzle upon activation.

Abstract: A tiller constructed in accordance to the present teachings includes a frame, a drive mechanism, and a tilling implement. The drive mechanism can be supported by the frame and include a motor having an output member. The tilling implement can have a drive shaft that is driven by the output member. The tilling implement can comprise a first tine plate and a second tine plate that are both selectively configurable along the drive shaft at a plurality of positions and orientations.

Abstract: An implement capable of being attached to a power machine having a mounting portion and a tool portion. The mounting portion is configured to engage with, and be secured to, an implement carrier on the power machine. The tool portion is capable of performing a work function. The implement has a joint for attaching the tool portion to the mounting portion and an actuator having first and second ends with the first end attached to the mounting portion at a first actuator attachment point and second end attached to the tool portion at a second actuator attachment point. The tool portion is capable of rotating about an axis that extends through the joint. The joint is capable of pivoting so that the axis about which the tool portion rotates is rotatable with respect to the tool portion.

Abstract: An electrical power tool may include an electric motor, a speed change device, and a battery pack. The speed change device is capable of changing a reduction ratio thereof and capable of automatically switching between a high speed low torque mode in which a high speed low torque is output and a low speed high torque mode in which a low speed high torque is output, based on an external torque applied to a spindle. A distance from the axis to a center of gravity of the battery pack and a mass of the battery pack are set such that an inertia moment around the axis is greater than a reaction around the axis that is produced when the high speed low torque mode is changed to the low speed high torque mode in the speed change device.

Abstract: According to an aspect of the present invention, there is provided a rotary striking tool includes: a motor; an oil pulse unit that is driven by the motor; an output shaft that is coupled to the oil pulse unit so that a tip tool can be attached to the output shaft; a first detection unit that detects a rotation angle of the motor and outputs a first output signal; a second detection unit that detects an impact generated at the oil pulse unit and outputs a second output signal; and a control unit that controls a rotation of the motor, wherein the control unit uses a portion of the second output signal based on the first output signal for control of the rotation of the motor.

Abstract: The cover is provided with engaging pieces that engage with a recessed groove provided on the outer peripheral surface of a hammer case and hold the cover on the hammer case to prevent the cover from being detached. The cover is also provided with bumper receiving portions extending from the front end of the cover and allowing the bumper to be externally attached to the cover, and engaging claws formed on the bumper receiving portions and engaging with engaged recessed portions formed on the inner peripheral surface of the bumper for holding the bumper to prevent the bumper from being detached from the cover. The cover with the bumper attached to the bumper receiving portions is provided to the hammer case.

Abstract: A system for offshore disposal of drill cuttings including a cleaning system for treating contaminated drill cuttings into drill cuttings and contaminants; a transport system for moving the drill cuttings; a slurrification system for making a slurry of the treated drill cuttings; and a cuttings re-injection system for injecting the slurry into a well.

Abstract: Generally, the present invention provides drilling fluid additives for reducing or controlling lost circulation in a drilling operation. The additives comprises particles. The particles comprise one or more solids in association a wax or waxy substance. A drilling fluid comprising a drilling fluid additive of the invention is also provided, as well as a method and use of the drilling fluid additive in a drilling operation to reduce or control lost circulation. Methods for manufacturing the drilling fluid additives are also described.

Abstract: A turbine drill motor capable of operation at ultra-high rotary speeds (i.e., in excess of 1000 rpm, which is very high for turbine drill motors), with a high-pressure jet-assist functionality for drilling and well service applications. The ultra-high rotary speed enables fast penetration with diamond bits, while the high-pressure jet-assist ensures adequate cooling and cuttings removal. In an exemplary embodiment, such a turbine drill motor includes a bypass channel to divert a portion of the driving fluid supply when the bit is off-bottom, to limit the no-load runaway speed of the turbine. Serial and parallel flow paths can be accommodated, and different drill bits for cutting and well-bore servicing are disclosed.

Abstract: A compact gas turbine motor and a speed reduction transmission capable of providing the speed and torque required for drilling with center discharge bits. The transmission includes two sun gears of different pitch diameters, keyed to the turbine shaft. Upper planet gears, whose carrier is fixed in place, drive an outer ring gear, which engages lower planet gears having a different pitch diameter. The lower planet gears engage the lower sun gear. Due to the different pitch diameters of the sun gears and planet gears, the gear carrier for the lower planet gears rotates in the same direction as the turbine shaft, but at a much slower rate. Exhaust gas from the turbine can be directed through one or more flow restriction elements to increase gas density in the turbine, further reducing turbine speed. The flow restriction element can comprise a venturi, to provide a vacuum assist to remove cuttings.

Abstract: A force compensator for a top drive assembly includes a carrier block, a pair of top drive link assemblies, a mandrel, and a shock absorber assembly. The top drive link assemblies being positionable on either side of a power swivel and having a lower end connectable to the power swivel, an upper end connected to the carrier block, and being slidably positionable on a derrick of a drilling rig. The mandrel is slidably disposed through the carrier block and has an upper end connectable to a mover assembly of the drilling rig. The shock absorber assembly is interposed between the carrier block and a lower end of the mandrel in such a way that the shock absorber assembly is movable between an expanded condition and a compressed condition.

Abstract: A rolling cone drill bit for cutting a borehole comprises a rolling cone cutter mounted on a bit body and adapted for rotation about a cone axis. Further, the bit comprises a tooth extending from the cone cutter. The tooth includes a base at the cone cutter and an elongate chisel crest distal the cone cutter. The crest extends along a crest median line between a first crest end and a second crest end and includes an elongate crest apex. The tooth also includes a first flanking surface extending from the base to the crest, and a second flanking surface extending from the base to the crest. The first flanking surface and the second flanking surface taper towards one another to form the chisel crest. Moreover, the tooth includes a first raised rib extending continuously along the first flanking surfaces and across the chisel crest to the second flanking surface.

Abstract: A downhole tool for bidirectional reaming of a wellbore with a tubular body with a central cutting section between a first end segment and a second end segment, wherein the central cutting section has a plurality of helical blades separated by flute sections, and wherein the helical blades each have at least two spiral angled sections connected together, polydiamond cutter nodes, high strength carbide cutting nodes, tungsten carbide hardfacing coating or combinations thereof on the helical blades, and wherein the outer diameter of the central cutting section is larger than the outer diameter of each of the end segments.

Abstract: A lawnmower drive system for facilitating steering of a zero turn radius lawn mower and enhancing user comfort while mowing a lawn includes a lawnmower has a seat for supporting a person on the lawnmower. The lawnmower has a left drive wheel and a right drive wheel. A left armrest is coupled to the lawnmower. The left armrest is positioned proximate the seat. A right armrest is coupled to the lawnmower. The right armrest is positioned proximate the seat. A left joystick is coupled to the left armrest. The left joystick is operationally coupled to the left drive wheel. A right joystick coupled to the right armrest, the right joystick is operationally coupled to the right drive wheel.

Abstract: A width variable structure using mecanum wheels is provided, which includes a plurality of mecanum wheels, a plurality of links connecting the mecanum wheels, and motors mounted on the mecanum wheels to transfer driving forces to the links, respectively. Since the width of the structure in the horizontal and vertical directions can be adjusted using the driving forces of the mecanum wheels, components such as actuators are omitted in the overall assembly.

Abstract: A tracked vehicle (e.g., a tracked carrier vehicle) comprising a plurality of track assemblies for traction of the tracked vehicle. Each of the track assemblies supports a portion of a weight of the tracked vehicle when the tracked vehicle is in use. Each track assembly comprises: a first wheel and a second wheel spaced apart from one another along a longitudinal direction of the tracked vehicle; a number of support wheels arranged in an in-line configuration between the first wheel and the second wheel; and an endless track disposed around the first wheel, the second wheel, and the support wheels. The support wheels may comprise at least five (5) support wheels mounted such that, when the tracked vehicle is in use, the portion of the weight of the tracked vehicle supported by the track assembly is never applied to only one of the support wheels.

Abstract: A working vehicle is structured to maintain a ride quality for an operator on a control seat. Provided are a travel machine body which mounts an engine, front wheels on the machine body, a track frame on the machine body, right and left travel crawlers installed on the track frame, a rear axle which transmits a rotating force to the travel crawler, and oscillation supporting point shafts which support the track frame on the machine body so as to freely oscillate. In the case that the rear axle and the oscillation supporting point shafts are provided so as to be spaced, the oscillation supporting point shafts are arranged just below an axle case to which the rear axle is pivoted, and the track frame is connected to the axle case via link members provided in the oscillation supporting point shafts.

Abstract: Apparatus for moving a wheeled load comprising: a frame having a two end; at least one wheel attached to at least one frame end; drive wheel(s) between the ends; a drive means for providing drive wheel power; a power source; a load-lifting arm means, the lifting arm means having a proximal end rotatably attached to the frame and a distal end; affixed to the distal end is a locking pickup head having a multi-socket center adapted to receive a ball, and a sliding locking gate to releasably affix the head to the ball; extending outwardly from the second end is a handle; disposed on the handle is a control means for operating the apparatus; and drive disengagement means for mechanically disengaging the powered driving mechanism so that a user can manually move the apparatus in case of battery or other mechanical failure.

Abstract: Provided is a vehicle-installation structure for a fuel cell with the capability of reducing a pressure drop in a gas flow path in the fuel cell. A vehicle-installation structure for a fuel cell in which: a fuel cell stack with an end of cells in a stacking direction being supported by an end plate is installed in a vehicle so that the stacking direction of the cells extends along a right-left direction of the vehicle; and an off gas of an oxidant gas from the fuel cell stack is exhausted via a diluter from a rear side with respect to the fuel cell stack in a front-rear direction of the vehicle, wherein a junction between a plurality of exhaust manifolds for guiding the off gas of the oxidant gas discharged from the fuel cell stack is arranged on a front side in the end plate in the front-rear direction of the vehicle.

Abstract: A drive system for an electric battery powered vehicle including a chassis having a rigid frame, a front axle and a rear axle; a battery system mounted on said chassis; left and right wheels on left and right sides of each of the front axle and the rear axle; one or more motors attached to at least one of the wheels. Each of the one or more motors is driven by rotation of a respective wheel to produce a charge for said battery system.

Abstract: An intake system of combustion air is provided for a vehicle. The intake system has an intake opening, an intake duct, and an air filter. The intake opening is situated on one side of a water separation container, which is fixed on a girder of the vehicle. The intake opening is situated in a front most front face of the vehicle in the travel direction for this purpose.

Abstract: This fuel cell vehicle FCV is provided with a fuel cell FC as well as a first tank and a second tank, which store a reaction gas to be supplied to the fuel cell FC. The first tank and the second tank are arranged in the front area of the fuel cell vehicle FCV. The second tank is arranged nearer to a rear area than the first tank and arrangement is performed so that the positions of the tanks are out of alignment in a vertical direction. This configuration enables compatibility to be ensured between an increase in the tank capacity of the fuel cell vehicle and an increase in the space in a passenger room and a trunk, and is capable of absorbing the impact of a collision even if the collision occurs.

Abstract: The invention relates to a vehicle suspension device for a vehicle seat (4, 4a, 4b) or a vehicle cab (3) comprising a lower part (20) and an upper part (4a, 4b) spring-mounted relative to the lower part (20) by means of at least one spring device, wherein the upper part (4a, 4b) is mounted relative to the lower part (20) in such a way that it is pivotable (17) about an imaginary or real axis (15) extending in the vehicle width direction or vehicle length direction (8) when vibrations occur between the upper part (4a, 4b) and the lower part (20).

Abstract: A movable rack system able to carry out a widthwise shift control of a movable rack without using a sheet rail member to be detected. The system is so configured, that magnets are placed at stop positions of the movable rack on the floor surface as members to be detected, while the movable rack is equipped with magnetic sensors to detect the magnets. When the movable rack stops traveling, the magnetic sensors detect the magnets and compares the detected magnetic intensity to the magnetic intensity detected at the previous stop. If the change exceeds a pre-determined value, namely the widthwise shift exceeding a pre-determined value is detected, a travel route of the movable rack to eliminate the widthwise shift is determined. In the next travel of the movable rack the rotation speeds of the respective driving motors are controlled so that the movable rack follows the travel route.

Abstract: A suspension system for a snowmobile has a rail and first and second suspension arms having lower ends pivotally connected to the rail. A first shock absorber pivotally connected between the first suspension arm and the rail. A second shock absorber operatively pivotally connected between the first suspension arm and the rail. Left and right brackets are connected to the second suspension arm. Left and right tie rods have lower ends operatively pivotally connected to the first suspension arm and upper ends pivotally connected to their corresponding brackets about a first pivot axis. The second shock absorber is disposed laterally between the left and right tie rods. The suspension is movable between a first position where the first pivot axis intersects the second shock absorber and a second position where the first pivot axis is spaced from the second shock absorber.

Abstract: A system that steers the rear wheels of the three wheeled vehicle in coordination with the operator turning the front wheel that improves handling, performance and safety. The rear wheels are steered by a rear end mounted powered steering rack that is controlled by a steering control computer that receives input from a variety of sensors including a sensor for vehicle speed and a sensor in the steering neck that measures the angular rotation of the handlebars as they are turned by the operator. Based on these inputs, using proprietary programming the steering control computer calculates the rate, timing and direction to turn the rear wheels. Rear steering offers advantages over front wheel only steering including being easier for the operator to turn the vehicle, a smaller turning radius, better straight line stability, better high speed handling, improved corning performance, improved steering response and improved safety.

Abstract: A rear suspension of a three-wheeled car with two front wheels and one rear wheel installed in the car body frame may include a pair of roll links that may be connected to the front wheels and twists as the car turns, and a roll connector that pivots around a shaft as the roll links twist, and a knuckle assembly, which may be joined to a rear wheel, installed in the rear end of the car body frame, and connected to a roll connector so that it turns left and right as the roll connector turns, wherein the knuckle assembly turns in the same direction the front wheels turn.

Abstract: An axle assembly for a motorcycle having a plurality of drive wheels. The axle assembly is configured to permit a user to replace an endless power-transmitting element without substantially disassembling the axle housing assembly.

Abstract: A vehicle shroud can have an opening formed so as to extend in a substantially front-to-rear direction. A substantially horizontal portion of a front fender of the vehicle can be located frontward of the opening. The vehicle can be a motorcycle, for example.

Abstract: Provided an electrically-operated hydraulic actuator unit that includes an electrically-operated motor controlled by a control apparatus and actuating a volume adjusting mechanism through driving-side and driven-side arms, and a clutch mechanism in which the driven-side arm presses a contact member against a clutch case so that the driven-side arm is locked when a force from the volume adjusting mechanism is applied to the driven-side arm. The control apparatus can set duties of first to fourth drive signals to be output to the electrically-operated motor in a neutral-side start period, a neutral-side ordinary actuation period, a higher-volume-side start period and a higher-volume-side ordinary actuation period. The duties of the first and fourth drive signals are larger than that of the second drive signal, the duty of the third drive signal is larger than that of the fourth drive signal, and an integrated ON-time of the third drive signal is larger than that of the first drive signal.

Abstract: A motorcycle is provided that includes a connecting pipe, a throttle body, an intake pipe, and an air cleaner, which are intake system parts disposed forward of a cylinder of an engine and are connected to the front side of the cylinder. The motorcycle further includes an exhaust pipe and a muffler, which are exhaust system parts connected to the rear side of the cylinder. The cylinder is inclined rearward, and the exhaust pipe of an exhaust system part extends forward along one side of the motorcycle in a widthwise direction of the engine 50 and detours the front of the engine and then extends rearward along the other side of the motorcycle in a widthwise direction of the engine.

Abstract: An upper limit speed control part controls the lower limit of motor displacement in conformance with the target upper limit speed via a motor displacement control part when the target upper limit speed is within the normal speed range. The upper limit speed control part controls the upper limit of pilot pressure via a pilot pressure control part in conformance with the target upper limit speed when the target upper limit speed is within the low speed range. Further, when the target upper limit speed is within the low speed range, the upper limit speed control part controls a pilot pressure valve such that the upper limit of pilot pressure increases as drive circuit pressure increases.

Abstract: A steering device for adjusting a wheel turning angle of a wheel of a motor vehicle, in particular of a rear wheel, includes a wheel guide member via which a wheel carrier of the wheel is connected to a vehicle body, the wheel carrier being swivellable about an axis of rotation disposed parallel to the wheel plane and the wheel guide member being articulated to the wheel carrier at a distance from the axis of rotation and being adjustable in length by an electromechanical drive unit, the electromechanical drive unit being connected, on the one hand, via a push rod to a joint at the wheel carrier end in order to form a swivel bearing to establish a connection to the wheel carrier, and, on the other hand, to a joint at the vehicle body end to form a further swivel bearing to establish a connection to the vehicle body.

Abstract: A hearing protection process comprises (a) providing at least one hearing protection device comprising at least one sound barrier comprising at least one substantially periodic array of structures disposed in a first medium having a first density, the structures being made of a second medium having a second density different from the first density, wherein one of the first and second media is a viscoelastic medium having a speed of propagation of longitudinal sound wave and a speed of propagation of transverse sound wave, the speed of propagation of longitudinal sound wave being at least about 30 times the speed of propagation of transverse sound wave, and wherein the other of the first and second media is a viscoelastic or elastic medium; and (b) interposing the hearing protection device between an acoustic source and an acoustic receiver in the form of a human ear.

Abstract: A high frequency horn for use in a multiple frequency loudspeaker system having a midrange transducer and a high frequency transducer is disclosed. The high frequency horn includes a horn chamber, horn mouth, a horn throat, a tuned resonant cavity, and a port connected to both the tuned resonant cavity and the horn chamber. The horn throat and horn chamber are located on opposite sides of the horn chamber, the port is located proximate to the horn throat, and the horn throat is configured to be connected to the high frequency transducer. The tuned resonant cavity is tuned to reduce high frequency standing waves produced by the midrange transducer within the horn chamber.

Abstract: An exhaust apparatus for internal combustion engines which can reduce exhaust noises, its weight and production cost with no need to provide a sub-muffler. The exhaust apparatus is provided with an inner pipe having the upstream open end and the downstream open end is disposed in the tail pipe, and the upstream open end of the inner pipe is protruded outwardly from the inside of the tail pipe to be extended into the resonance chamber, and thus the upstream open end is closed by the resonance chamber defined by the outer shell of the muffler, the end plate, and the partition plate.

Abstract: A honeycomb structure that includes cells in which septums are located to provide acoustic dampening. The cells are formed by at least four walls wherein at least two of the walls are substantially parallel to each other. The septums include warp fibers and weft fibers that are substantially perpendicular to each other. The septums are oriented in the honeycomb cells such that the weft fibers and/or warp fibers are substantially perpendicular to the parallel walls.

Abstract: A wedge-shaped, number theoretical acoustic diffuser both diffuses and reflects sound while eliminating wasted space created by prior art. The inventive diffuser consists of wells of continuously variable depths which provide wide-bandwidth diffusion in a single dimension. The back of the wells are reflective planes of a plurality of angles that direct energy away from the sound source. The invention may be installed in the upper corners of a room, with the deepest end of the wedge-shape up and tapering down to the thinnest end of the wedge shape. This installation allows floor standing furniture or other objects to be placed against the wall, an impossibility with the installation of prior art. The present invention may be installed as an array in which the deepest ends of the wedge shape are butted together. This formation splits and reflects sound in two different directions both away from the sound source.

Abstract: A multilayer laminate comprising in order, a polymeric film layer capable of withstanding a temperature of at least 200 C for at least 10 min, an adhesive layer having an areal weight of from 2 to 40 gsm capable of activation at a temperature of from 75 to 200 degrees C. and an inorganic refractory layer.

Abstract: A multilayer laminate comprising a first polymeric film layer capable of withstanding a temperature of at least 200 C for at least 10 min, a first adhesive layer having an areal weight of from 2 to 40 gsm capable of activation at a temperature of from 75 to 200 degrees C., an inorganic refractory layer, a second adhesive layer having an areal weight of from 4 to 40 gsm capable of activation at a temperature of from 75 to 200 degrees C. and a second polymeric film layer capable of withstanding a temperature of at least 200 C for at least 10 min, wherein at least one of the first or second polymeric film layers is thermoplastic.

Abstract: A multilayer laminate for use as a flame barrier in an aircraft comprising a polymeric film layer capable of withstanding a temperature of at least 200 C for at least 10 min, an adhesive layer, an inorganic refractory layer and an aramid paper comprising from 50 to 90 weight percent of aramid fibers and from 10 to 50 weight percent of meta-aramid binder.

Abstract: A moldable acoustic facing comprises cellulosic fibers and synthetic fibers entangled together. The acoustic facing has a basis weight of from about 1.5 to about 5.0 ounces per square yard (osy), a thickness of less than about 0.050?, a mean pore size of between about 8 microns and about 40 microns, and an elongation at break of at least twenty percent. The acoustic facing includes less than about five percent synthetic microfiber and has an acoustic resistance of at least about 250 Rayls.

Abstract: The invention relates to an extendable/retractable ladder mounted to a boat trailer to allow access to a boat carried on the trailer. The ladder includes a pair of first vertically oriented bars and a pair of second bars. The vertically oriented bars have an inner cavity and a slot in one of its sides. The second bars have an inner cavity and a slot in one of its sides. The first end of the first bars and the second end of the second bars are connected such that the second end of the second bars can move along the length of the first bars between an extended position in which the first end of the second bars is a distance away from the first bars and a retracted position in which the first end and the second end of the second bars are adjacent to the first bars.