Abstract: A multi-stand rolling mill is operated so that strip of suitable shape and metallurgical properties is produced at a faster speed than possible heretofore by threading the mill at a relatively slow speed and adjusting the rolling loads on the stands to give the required output gauge and rolling temperature at the last stand, thereafter the mill is accelerated and curtains of liquid coolant are applied to the workpiece at one or more interstand locations to ensure that the rolling loads remain substantially the same as when threading and the rolling temperature of the last stand remains substantially constant.

Abstract: Apparatus for making a spindle-type body with at least one eccentric zone from a semi-product of circular cross-section by gradually radially displacing the eccentric zone of the semi-product to bring its eccentricity from zero to the desired value. The apparatus includes a multi-part die with shaping jaws providing a semi-product shaping passage therein, the semi-product being thrust axially into the die while the semi-product and the die rotate relatively to each other.

Abstract: A pull-back type indirect extrusion press is designed so that the scalping of billets can be effected inside the press independently of extrusion cycles and the scalped billet is allowed to stand by in a billet extrusion standby space which is provided with a heating element to heat the standby billet to maintain the same at a required temperature and into which a billet oxidation-preventive gas is admitted to prevent oxidation of the standby billet.

Abstract: A tube bender construction for manual operation in bending a tube. The tube bender includes a mandrel defining a bending groove into which the tube is urged by a forming member mounted to the mandrel to swing about a bending axis of the bending groove. The tube to be bent is held against longitudinal and rotational movement during the bending operation by tube holding structure arranged to clamp the tube against an extended groove portion of the mandrel. Movement of the forming member about the bending axis is effected by manipulation of a pair of handles. The tube clamping structure includes a hook which is swingably mounted to the mandrel and adjusting structure is provided for adjusting the disposition of the swingable hook to provide a desired clamping force of the hook against the tube. The illustrated adjusting structure includes an eccentric pin and structure for locking the pin in adjusted positions.

Abstract: A tube bender construction for manual operation in bending a tube. The tube bender includes a mandrel defining a bending groove into which the tube is urged by a forming member mounted to the mandrel to swing about a bending axis of the bending groove. The tube to be bent is held against longitudinal movement during the bending operation by tube holding structure arranged to retain the tube against such movement. Movement of the forming member about the bending axis is effected by manipulation of a pair of handles. The mandrel defines an extension adapted for adjustably mounting the tube holding hook to further define structure for adjusting the disposition of the tube to be bent to be accurately tangential to the bending groove at a bend start position thereof.

Abstract: A novel testing system utilizing a novel subcombination multiple pin/probe ype, motion-sensing accelerometer transducer, capable of sensing exceptionally high levels of structural motion, in the domain of from about 1,000,000 to 10,000,000 Gs (force of gravity). Such motion may be imparted by shock wave forces generated by detonation of high energy ballistic and/or land mine charges, thereby generally deforming some portions of closely adjacent, high strength structures such as steel armor plate being tested. This novel accelerometer transducer comprises at least two and preferably from six to eight potentially deformable pin-like contact probes preferably of pure annealed metal which preferably project from both sides of a support fixture. One set of contact pin ends are generally spaced at slightly different distances from an adjacent surface to be tested.

Abstract: An apparatus for compensating for changes in the mass flow rate of a sample gas stream in gas analysis instruments having outputs that are calibrated in terms of the concentration of a component of the sample stream. In instruments in which a pressure regulated sample gas stream is applied to a detector assembly through a flow restrictor such as a sample capillary, a gas flow sensor is connected in series with the flow restrictor to develop a correction signal that varies in accordance with the mass flow rate of the sample stream. A correcting circuit combines the correction signal from the flow sensor with the output signal from the detector assembly to produce a corrected output signal that correctly indicates the concentration of the component of interest.

Abstract: A knock detecting apparatus includes a vibrating means having a plate reed member adapted to vibrate in response to the vibrations of an internal combustion engine and a support member which is greater in thickness than the reed member and adapted to support the reed member, the reed and support members being made integrally from a magnetic material. When the reed member resonates upon the occurrence of knocking in the engine, the resulting change in the magnetic reluctance of the magnetic path including the reed member is sensed by a sensing coil to thereby detect the knock. The magnetic flux in the magnetic path is generated by a magnet or an excitation coil. An impedance element may be connected to the sensing coil or the excitation coil so as to correct variations in output from one coil to another.

Abstract: A metallic reed clamped against a piezoelectric element, and free to oscillate at its other end, generates electrical signals in a piezoelectric element which is held between clamp surfaces in fixed relation to an engine part which transmits engine knock vibrations to the sensor assembly. The reed is oriented perpendicular to the vibratory motions of the engine part on which it is mounted, so that vibrations of the reed will be excited thereby, and these will deform the piezoelectric element to generate signals. The entire assembly can be enclosed in a transverse bore in the head of a cylinder head screw.

Abstract: A force transducer, particularly for the ballistic measuring of the combustion pressure in the cartridge case of a firearm, is disclosed which includes a force transmission element which rests with one of its front areas on the cartridge case. The force transmission element is surrounded on its exterior by an outer sleeve which also rests with its front area on the cartridge case. The front areas of the force transmission element and of the outer sleeve are exactly adapted to the curvature of the cartridge case by reaming after the transducer has been mounted in the firearm. With the combustion of the powder, the cartridge case expands and transmits its force to a sensor element via the force transmission element, with the sensor element being preferably in the form of at least one piezoelectric transversal quartz element which is held under pretension between the force transmission element and a basic receiver component.

Abstract: Sensor and method of fabricating a sensor for detecting relative humidity with a substantially linear response from 0% to 100% and also detecting temperature. The sensor utilizes a unique essentially pure Al.sub.2 O.sub.3 layer which has a disordered crystalline structure and a density gradient which varies from a low density at its lower surface to a higher density at its upper surface which together produce the desired linear response to relative humidity.The sensor is employed as a three-terminal semiconducting device which is biased with d.c. current, allowing implementation with standard ICs and LSI circuitry. Application of a biasing current on the top electrode allows the RH sensor to be operated simultaneously as a temperature sensor.Also disclosed is a relative humidity detector system for adjusting sensitivity of the sensor for changes in environmental temperature so as to provide a true linear relative humidity response. Periodic discharge of the d.c.

Abstract: A confining pressure system includes a pressure cell containing a mechanical oscillator and a gas supply for carrying out resonance measurements of rock material under confining pressure at seismic frequencies. An appropriate gas is used to avoid significant damping of oscillations under confining pressures of various ranges.

Abstract: There is disclosed herein an ultrasonic system for detecting internal discontinuities in a body. The system includes: an ultrasonic transducer for directing sonic energy toward a body; a liquid crystal, acousto-optical detector cell for detecting ultrasonic energy passing through said body; an optical system for illuminating said liquid crystal cell; and a liquid medium for coupling the transducer body and cell.The acousto-optical cell includes a pair of substantially rigid covers, a liquid crystal material positioned between said covers and a peripheral spacer and sealing member surrounding said liquid crystal and sealingly engaging said covers. Each of the covers is substantially acoustically transparent and at least one of said covers is optically transparent. The optically transparent cover is a laminate having at least three layers, with each of said layers of said laminate having a thickness much much less than 1/4 of the wave length of the ultrasonic energy propagating through said layer.

Abstract: Laser light for producing acoustic waves in a specimen to be examined is carried to the specimen from a single laser by a plurality of fiber optic cables. The fiber optic cables have different path lengths to cause a specific time delay between adjacent fiber optic cables to focus and steer the sonic waves in a desired direction.

Abstract: A battery electrode fatigue simulator having a frame which supports therein a pivotal and a stationary beam. The pivotal and stationary beams secure therebetween an electrode plaque which is to undergo the fatigue simulation. Also mounted to the frame is a rotatable cam of predetermined dimension which acts upon a cam follower forming part of the pivotal beam thereby causing cyclic movement or displacement of the pivotal beam. This cyclic displacement is transferred to the plaque as a cyclic stress in tension. Measurements are made of the displacement of the pivotal beam as well as resistance of the plaque during the application of the cyclic stress. The cyclic displacement versus resistance relationship is representative of the fatigue a battery electrode will undergo during actual battery operation.

Abstract: A flow transducer for measuring the flow of a fluid, the transducer including a housing having two spaced apart depending legs with a shaft rotatably mounted between the legs, and a rotor secured on the shaft for rotation by the flow of fluid thereacross. In one of the legs is provided a chamber which houses a magnetic device also secured on the shaft for rotation with the rotor. The magnetic device produces a change in a magnetic characteristic as a function of the rotation of the rotor. A suitable sensor is contained in the housing adjacent to the magnetic device, and produces an electrical output responsive to the change in the magnetic characteristic.

Abstract: A tube closed at the end by plugs having axial bores therein and which support a hollow, porous walled cylinder concentrically within the tube to form a conduit interconnecting the plug bores while allowing a clearance space between the cylinder outer wall and the tube inner wall. A combined ejector-blowback valve is secured to one plug externally of the tube for inducing gas flow through the plug bores and cylinder in one valve position and for reversing flow through the plug bores and cylinder in a second valve position to dislodge and discharge adherent material. The probe is mounted with the end opposite the ejector-blowback valve extending into the gas stream to be sampled. Gas samples are withdrawn from the clearance space surrounding the cylinder. The probe is constructed substantially entirely of corrosion and temperature resistant ceramic material.

Abstract: A drive unit is disclosed having interlocking members for directly connecting angularly disposed drive and driven shafts. The interlocking members comprise conventional pinion mate and side gear blanks supported in a standard differential housing driven by a drive shaft through a ring and pinion gear set. Pinion mate gear blanks are connected by the usual cross shaft to the differential housing. Side gear blanks cooperate with the pinion mate gear blanks and are connected to the driven shaft. Integral locking surfaces provided on the mating gear blanks cooperate to prevent the side gear blanks from rotating relative to the differential housing so that a direct drive power path is established between the drive and driven shafts.

Abstract: A high ratio speed reducer comprising a rotatable input shaft operatively coupled to an output shaft which rotates at a reduced speed in response to rotation of the input shaft. An output sprocket is mounted on the output shaft for rotation therewith, the output sprocket having a circumferential perimeter including a number of teeth. A drive sprocket having a circumferential perimeter including a number of teeth differing by at least one tooth from the number of output sprocket teeth is rotatably mounted with respect to an eccentric end portion of the input shaft and orbits as the input shaft is rotated. Successive segments of the drive sprocket perimeter continuously move outside the output sprocket perimeter as the drive sprocket orbits to advance an endless double chain engaging both sprockets.

Abstract: An automatic turret lathe in which sequences are manually programmed for automatic control (both turret and cross slide) as an incident to setting up the machine, requiring neither tape nor card programs but rather the manual effort of the machinist; the lathe also incorporates a unique clutch and bearing support for the rotary turret, and the turret has a positive lock for accurately holding the index position; all essential functions and modes including feed rates and r.p.m. are visually displayed.

Abstract: A foodstuff such as a sausage is sliced in a predetermined slicing direction into a succession of slices each having a respective width measured parallel to the slice direction. This succession of slices is then deposited on a support in a plurality of rows with the slices in each row offset from one another by a predetermined first distance and the rows offset from each other by a predetermined second distance. The width of the slices is continuously measured as they are cut and at least one of the distances is automatically varied in dependence of the measured width to produce a uniformly overlapping array of slices. In addition the machine can calculate the weight of a given slice by combining the width with the slice thickness and the slice density, and this weight can be divided into a desired weight to determine how many slices at the predetermined size are needed to make up the desired weight. A signal can indicate then when this weight is reached.

Abstract: A cutting tool arrangement for performing the process of opening up the slit cut in the workpiece by circular saws before the saw is retracted to facilitate removal of the saw. The workpiece being severed is moved perpendicular to the cutting plane as is the saw blade to accomplish the desired result.

Abstract: A safety boot assembly for use with a press brake operated C-frame punch or the like tool which fits between the ram of the press and the upper arm of the C-frame to prevent a human limb from being inadvertently placed in any gap between the ram and C-frame. The disclosed assembly includes a corrugated boot and end fittings to attach its ends to the ram and C-frame.

Abstract: A panel grooving apparatus has a table for supporting a panel at a working level. A rail extends along a side of the table and a working assembly is mobile on that rail. The working assembly is selectively immobilized in various grooving positions by stops movable and selectively arrestable along the rail and engageable by part of said working assembly. The panel is releasably retained on the table by movable peripheral elements thereon. In a simplified embodiment, the working table may be reduced to a ruler on which a shoe of a rectilinear guide slides.

Abstract: A keyboard operated electronic musical instrument is disclosed for imitating the strummed and solo modes of playing plucked fretted musical instruments. The actuated keys do not directly control the set of tone generators, but are used to automatically select one of a library of chord types which is closest to the actuated keys. A root note is chosen for each selected chord type. The selected chord type is transposed to an open chord spanning the several octaves associated with a guitar-type instrument. The selected tone generators assigned to the transposed open chord are strum keyed in sequence at a rate adaptive to the speed in which successive chords are entered on the keyboard. Provision is made for up-down strumming and to automatically enter a solo tone mode when a sequence of single notes are entered on the keyboard.

Abstract: An electrical pickup for a stringed musical instrument comprises a cylindrical permanent magnet and a coil surrounding the magnet and wound lengthwise thereof. The ends of the magnet are fixed to two rigid mounting wires, and the coil is wound on a former comprising a central tubular core and two parallel plates fixed to the tube on diametrically opposite sides thereof. The tube, and thus the former and coil as a whole, can turn on the magnet. The magnet is magnetized so that the magnetic poles thereof are positioned at diametrically opposite edges of the magnet, i.e. at the ends of a diameter of the circular cross-section of the magnet cylinder. Thus the former and coil can be turned between two positions 180.degree. apart in order to reverse the winding direction of the coil around the fixed magnetic axis H of the magnet.

Abstract: Simultaneously played notes on a keyboard are automatically provided with different voice timbres. The assignment of voices to notes is by relative frequency-scale position within the chord. If four or more notes are played, the notes are scanned along the musical scale and the three lowest notes played and the highest note are sounded in different voices with the solo voice assigned to the highest note. Assignment of voices occurs automatically when fewer than four keys are played. Time division multiplex digital logic signals representative of the played keys are applied to a memory circuit and a comparator circuit. If the information stored in the memory from the previous scan cycle is unchanged the comparator provides an enabling signal to a monostable and enable logic circuit. A priority selector circuit provides logic information to the monostable and enable logic circuit which outputs this information and information representative of the total number of keys played.

Abstract: A hydraulic amplifier having a housing provided with pressure and return conduits, an amplifier piston, and a control slide. The piston is slidably arranged in an axial bore of the housing and itself has a blind axial bore within which the control slide is arranged. The piston and slide together constitute a unit which is free of pressure equalization and which is provided with two sets of passages for selectively placing the face of the piston in communication with the pressure and return conduits, respectively, depending on the axial position of the slide in the blind bore of the piston. The passages are asymmetrical with respect to the peripheral surface of the slide and are so constructed and arranged that whichever set of passages is closed, the slide is pressed radially against the closed passage under the influence of certain pressure differences which prevail in the hydraulic amplifier.

Abstract: A device for limiting the stroke of a hydraulic ram of mining apparatus employs a segmental stop which partly surrounds the piston rod of the ram. The stop locates between the cylinder of the ram and a head piece at the end of the piston rod. The cylinder of the ram makes contact with the stop during retraction of the ram thereby limiting the stroke of the ram. The stop is connected to the head piece via replaceable or adjustable pins. These pins permit the distance between the head piece and the stop element to be altered at will. The connection pins also enable the stop to be arranged to partly surround the piston rod periphery over different regions thereof.

Abstract: A double-acting piston is provided which is slidably mounted within a cylinder bore formed within the framework of a swash-plate type compressor, for carrying out a fluid compressing action. The piston comprises a pair of piston heads provided at its opposite ends and an intermediate coupling member coupling the piston heads to each other. The piston heads and the intermediate coupling member are separately fabricated from discrete pieces by means of stamping or the like. The piston heads each comprise a hollow first part extending axially inwardly of the piston and a hollow cylindrical second part extending radially outwardly from an outer end of the first part and serving as a slider. The first and second parts of the piston heads may be separately fabricated from discrete pieces by means of stamping or the like.

Abstract: A truss-fabricating machine comprising a table for supporting a pair of parallel spaced-apart wood chord members, a series of web members spanning the chord members, and connectors having teeth adapted to be pressed into the wood chord members. The machine further comprises apparatus on the top of the table for clamping the chord members in fixed position with respect to the table, including a pair of outside jaws engageable with the outside faces of the chord members, and expansible tubing extending longitudinally of the table for effecting movement of the outside jaws relative to one another transversely of the table to clamp the chord members in fixed position with respect to the table. A press is movable longitudinally with respect to the table for pressing the teeth of the connectors into the chord members when the chord members are clamped in fixed position.

Abstract: Marking apparatus especially for applying identifying marks to large coils, has a base 26 which is reciprocatingly moved along a track past the surface to be marked. Mounted on the base, so as to be movable transversely with respect to the base's movement, is a marking carriage 30 carrying marking means 36,37. In order to increase the area which can be marked and in particular to apply two lines of text, the carriage is mounted on the base by means of at least two spaced apart swivelling arms 29 which form an articulated quadrilateral such that the carriage is movable transversely between two limit positions with respect to the path of movement of the base.

Abstract: An apparatus is provided, for use in an impact printer, in which printer it is required that an impact producing hammer, or assembly of such hammers, be operable in more than one location, whereby the hammer or assembly of hammers is moved between operational positions, the operation of the hammer or assembly of hammers is inhibited except when correctly positioned for operation, any mispositioning of the hammer or assembly of hammers is automatically corrected, wear, introduced by movement of the hammer or assembly of hammers, is minimized, and high operational speed, of the printer, is attained.

Abstract: A pullout shelf provided with rollers is mounted on static roller guide structure having several tracks with openings in the tracks to allow manipulation of the shelf and a supported machine to desired heights and inclinations.

Abstract: Shelving wherein bores are drilled in legs of channel-section-shaped shelving posts, between the legs of which is positioned channel-section-shaped crosspiece having obliquely downwardly and upwardly extending slotted crosspiece holes lying opposite the bores, and wherein a clamp bolt is placed in the bores in the slotted crosspiece holes, the bores and slotted crosspiece holes lying opposite one another.

Abstract: Shelving assembly includes vertically disposed corner posts interconnected at their bottom ends by base panels secured to the posts by disjointable connecting means and interconnected at their top ends by header panels disjointably secured to the posts together with a plurality of vertically spaced clips disjointably mounted to each post and arranged to support a plurality of shelves except for the bottom shelf which is arranged for disposition in a horizontal attitude and which also is tiltable by virtue of its support along its rear edge by a tilt beam, the shelf which is disposed immediately above the lowermost shelf being arranged to form a tiltable back portion for the device which is disposed in approximately perpendicular relation to the lowermost shelf when tilted.

Abstract: An article display stand is formed of one pair of identical semicylindrical vertical support members and one pair of identical horizontal support members. The horizontal support members have means thereon to hold the vertical support members in position. The vertical support members are preferably formed of transparent material to permit viewing therethrough.

Abstract: An incinerator having a generally cylindrical, horizontally disposed shell enclosed at its ends by vertical end plates and defining a combustion chamber. The upper sector of the shell is provided with a feed opening for introducing combustible waste into the housing and the opening extends continuously between the opposite end plates. Enclosing the feed opening is a generally curved door, the lower portion of which is hinged to the shell so that the door can be pivoted between a closed and open position. The gases of combustion are discharged from the combustion chamber through a stack and the upper portion of the shell bordering the stack can be formed with an enclosed heating jacket through which a heating medium can be circulated. Heat from the combustion of waste will act to heat the medium and the heated medium can be used for auxiliary heating purposes.

Abstract: A float is moved upwardly or downwardly by liquid being added to a liquid holding tank. The float carries a first permanent magnet which is moved by the float towards a second magnet which is separated therefrom by a liquid tight partition. The permanent magnets are arranged with like poles directed towards each other so that the permanent magnets will repel each other and movement of the first permanent magnet in response to a liquid level change will cause the second permanent magnet to be moved in response to the repelling force. The second permanent magnet is positioned in line with a depressable control member of a normally closed valve in a gas line. Movement of the second permanent magnet against such control member depresses the control member to open the valve, allowing gas to flow from a storage tank to a piston in a normally closed valve that is located in a second line leading from the gas supply to a horn.

Abstract: A drying oven for an indefinite length of material having a drying chamber surrounded by an annular heat exchanger, the drying chamber having an inlet and outlet for material passing through it. The heat exchanger has heat exchange members defining flow passages extending axially and around the chamber and having an incoming passage interconnected with an outgoing passage by means of the drying chamber.

Abstract: This disclosure is concerned with creating relatively darkened or light-shielded coverings along and upon a substantial selected area of the surface of a pond or other confined fish-holding water volume in the form of surface turbulence generated over said selected area by water spraying or other agitation, with calm illuminated feed zones adjacent but external to said selected area.

Abstract: This disclosure is concerned with utilizing the lower dark strata of deep sea cages and the like for fish, such as salmon, as a stress-relief resting volume, while providing specially contoured artificial illumination beyond daylight hours that is limited to upper strata of the cages where feed is periodically applied, and which illumination is prevented from penetrating into the dark strata, but rather provides a predetermined upper laterally illuminated feed-exposing strata, viewable diffusely from below by the fish in the dark lower resting strata.

Abstract: An improved horse therapy spa unit is provided which comprises a unitary housing which defines a preferably open-topped water-tight horse therapy compartment and integral hot water and cold water chambers on opposite sides thereof. A water heater and a water refrigerator are disposed in the housing. Water circulation pumps, valves and conduits interconnect the chambers, heater, refrigerator and horse therapy compartment. A water aerator is included in the circulation system and upper and lower sets of jet spray nozzles are positioned in the walls of the therapy compartment. A control panel on the outside of the housing controls the circulation and temperature regulating systems. A hand-held pulsed jet spray unit may be included in the housing, as may radiation lamps disposed in ports in the therapy compartment, a container for medicine and/or disinfecting chemicals, a feed bag and a feed storage compartment.

Abstract: An animal feeder for an animal cage assembly formed of a plurality of animal cages arranged side-by-side in a horizontal alignment. The animal feeder comprises a carriage which is mounted for horizontal movement along the cage assembly. A feed mechanism carried by the carriage dispenses feed into a feed trough mounted along the front of the animal cages as the carriage traverses the cage assembly. A control apparatus mounted on the carriage de-activates the feed mechanism when predetermined levels of feed remaining in the feed trough are detected. A detector carried by the control apparatus detects the level of feed remaining in the feed trough as the carriage traverses the cage assembly.

Abstract: An improved portable livestock spraying apparatus which includes a chute structure and adjustable guidance structure for directing different sizes of animals through the chute in the presence of surrounding spray coverage of selected medicinal solution. The apparatus includes floor structure for solution filtration which effects three-stage filtering of coarse, fines and final fluid output for recycling to the spray head apparatus.

Abstract: Improvement is introduced in a conventional feedback control system for supplying an optimal air-fuel mixture to an internal combustion engine on the basis of a sensed component of exhaust gases thereof.

Abstract: A compact fuel injection pump of the radial plunger type having a plunger barrel that integrates the plunger and a delivery valve in a common bore along with a fuel inlet-spill port in the wall of the barrel, the port being controlled by a ball valve actuated by a solenoid to a closed position to permit pressurization of the fuel for injection past the delivery valve, the ball valve being self-aligning.

Abstract: An air and fuel mixture heater for disposition between the usual opposing and coaction mounting flange portions of a combustion engine intake manifold and associated carburetor base mounting flange, and which heater basic structure and operation may also be incorporated in the inlet portion of the associated intake manifold, if desired, when carburetor air cleaner-to-hood clearance is minimal. The heater defines a thin hollow housing including a pair of closely spaced, parallel and registered opposite top and bottom side walls having at least generally registered air and fuel mixture openings formed therethrough. The housing also includes peripheral wall portions extending between corresponding peripheral edge portions of the housing side walls and baffle plate is mounted within the housing spaced intermediate and generally paralleling the housing side walls.

Abstract: A circuit to be utilized in combination with an ignition system which is responsive to a start signal supplied thereto for maintaining the ignition system in a start mode of operation while starting of the internal combustion engine is controlled by the ignition system. The circuit is responsive to termination of the start signal to provide transitioning of the ignition system to a run mode of operation only during the current ramping period when the ignition coil of the ignition system is being charged prior to the end of a firing cycle when the coil is discharged to provide spark to operate the engine. Start retard and transitioning of the system from start to run modes is provided utilizing a single capacitor.

Abstract: A rubber band rifle for shooting one or a plurality of rubber band members generally includes a body having a forward barrel portion and a rear shoulder portion having a plurality of horizontal grooves disposed therein, one end of each of the rubber band members being disposed in one of the horizontal grooves in the forward end wall, a slide mechanism being movably disposed on the forward barrel portion, the slide mechanism including a top and a pair of downwardly extending walls, an upper surface of the top of the slide mechanism having a plurality of notches therein, the other ends of the rubber bands being disposed in the notches, and a mechanism for locking the slide mechanism in a fixed position upon the barrel portion of the body.