Abstract: A rocket motor construction wherein a convolutely wound propellent strip forms a fuel grain disposed within the rocket motor casing. The fuel grain consists essentially of double base propellent having a plateau or mesa burn characteristic and is shaped to provide a plurality of rearwardly extending blades connected to a convolutely wound margin of the strip. The blades cooperate with each other and with the rocket motor casing to define flow channels between angularly adjacent blades and between adjacent convolutions thereby providing flow channels for combustion product.

Abstract: To supervise operational effectiveness of catalytic reactors included in exhaust emission detoxification systems, an oxygen sensor is located downstream of the reactor to determine oxygen content in the exhaust gases from the internal combustion engine, the oxygen sensor comprising an ion conductive solid electrolyte forming an ion concentration chain and having catalytically inactive contacts, connected to a detection circuit which provides an output signal in dependence on a signal from the sensor, the output signal operating an alarm, or a transducer which interferes with proper engine operation to force the operator to have the reactor repaired. Preferably, two ion conductive chains are used, in a single sensor, or in two sensors, one being exposed to exhaust gases upstream of the catalytic reactor and the other downstream of the catalytic reactor, the output signals being provided to a differentially connected operational amplifier, to balance out extraneous influences.

Abstract: A sensor such as an oxygen sensor or a carbon monoxide sensor generates an electrical signal responsive to the oxygen or carbon monoxide concentration in exhaust gases discharged from an exhaust purifying device. Under the control of the electrical signal regulating means the amount of secondary air to the exhaust purifying devices is regulated.

Abstract: An exhaust gas purifying system for use in an internal combustion engine for controlling the air injection into an exhaust manifold and the circulation of exhaust gases from the exhaust manifold to a suction pipe, due to a negative pressure prevailing in the suction pipe, in which the negative pressure varies depending on the running conditions of the engine.

Abstract: An insulated heat pipe is provided which transfers heat from the engine's exhaust manifold to an exhaust gas reactor. The heat pipe contains a first zone serving as an evaporation zone, a second zone serving as a transport zone for transporting a working medium between the first zone and a third zone. The third zone serves as a condensation zone. The heat pipe has an interior capillary tube along which the condensed heat transfer medium flows toward the heat source and within which the vaporized medium flows toward the heat sink.

Abstract: A hydraulic pump arrangement and control circuit for supplying fluid at high volume and high pressure to a work circuit. The system utilizes a fixed displacement pump, a variable displacement pump with a compensator, and a relief valve at a pressure setting higher than the variable displacement pump's compensator setting.

Abstract: A hydraulic circuit including a single pump and a plurality of control valves for communicating actuating fluid to the separate hydraulic motors from the single pump includes a synchronizing unit for initiating and terminating operation of the pump in response to operation of any of the control valves, the synchronizing unit including a pivotable gang plate adjustably mounting cam shoes separately associated with synchronizing levers connected to actuating elements for each of the control valves, the single gang plate thus being movable in response to operation of any one of the valves in order to initiate or terminate operation of the pump in closely synchronized relation to positioning of any one of the control valves to communicate the pump with one of the motors.

Abstract: A mixed loop hydrostatic transmission circuit for use principally with orbit, gear, vane and other non-piston type motors, which generate contaminants making them less suitable for applications using conventional closed loop hydrostatic transmission circuits. The mixed loop hydrostatic transmission drive retains the precise load control and high efficiency of a closed loop system, while introducing the benefits of contamination control of open loop hydrostatic transmission circuits. While maintaining the speed of the motor proportional to the output flow of the pump, both in positive and regenerative modes of operation, the full flow of fluid is diverted from the motor to the reservoir, while the full flow of fluid, required by the pump, is supplied directly from the system reservoir.

Abstract: Low pressure steam generated by a solar collector is compressed to raise its temperature and pressure. The compressor is driven by an engine which is, in turn, driven by a combustible fuel. Shaft work produced from the fuel is used directly to drive the compressor. The energy available from the steam is the sum of that resulting from both solar energy and combustion of fuel. The total amount of steam produced per Btu of heat generated by fuel input to the engine is substantially greater than the amount of steam that would be produced directly by combustion of the fuel.

Abstract: Rotary closed Rankine cycle cooling and heating apparatus utilizing a single fluid for both engine power and refrigeration. The apparatus includes a rotary housing containing a boiler, power fluid expander coupled with a refrigerant fluid compressor and a refrigerant expander. A condenser for the expanded power portion and the compressed refrigerant portion of the single fluid, and an evaporator for the expanded refrigerant fluid portion, are mounted at respectively opposite sides of the housing coaxially thereof for rotation with the housing as a unit. The power fluid expander is driven at a predetermined speed by pressure power fluid vapor generated in the boiler and in turn drives the refrigerant fluid compressor. The refrigerant expander is of the capillary type constructed and arranged with respect to the evaporator to automatically control the capacity balance of the refrigerant system.

Abstract: An oil fence having a unidirectional flexibility, comprising a plurality of rigid floats which are swingably connected by hinge means. Planar skirts are connected to the floats so as to define at least one continuous oil fence wall thereby.

Abstract: A fishway comprising a channel having spaced-apart side walls and an interconnecting bottom wall for conducting a flow of water therethrough, a plurality of longitudinally spaced vortex generators formed on each channel side wall for providing reversing vortices in the flow stream of water along the channel whereby alternately reversing cross-stream water flows and upstream water flows are created to assist fish using the fishway in upstream travel. The vortex generators are provided by uniformly spaced baffles extending alternately from the channel side walls. The channel can be straight or curved in the form, for example, of a helix.

Abstract: An off-shore power plant in which the steam generators of the power plant are located within the support structure carrying the components of the power plant. The steam generator is operated with superpressure in the combustion chamber. A gas turbine is connected to the flue gas smoke stack of the combustion chamber, and a steam turbine is connected to the steam duct of the chamber. The support structure holding the steam generator carries a platform with several decks. The water treatment and gas purification equipment is located on the lower deck, whereas the upper deck carries the turbines and the generators.

Abstract: A maritime assembly incorporating a foundation raft for founding, or when founded, on a sea bed, and having venting means responsive to the movement of waves whereby pore pressure at at least one point beneath the raft is reduced with respect to the hydro-static pressure appropriate to the external depth of water below the mean level of water in which the raft is (to be) founded.

Abstract: A concrete pile or like concrete column formed in earth situs by rotating a continuous flight auger consisting of one or more sections into the earth to form a cavity of given depth; rotating the auger to remove augered earth from the cavity without removing the auger therefrom, and replacing the removed earth from the auger flights with fluid cement mortar, which hardens to form a column reinforced by the auger resultantly anchored in the same. A plurality of short auger sections may be connected together in succession during drilling to form a cavity of requisite depth by increments when low headroom conditions exist. A portion of the auger or a shaft portion without auger flighting thereon may also protrude above the earth situs for extension through water and the like and be filled with cementitious material which is allowed to harden.

Abstract: Hollow casings containing a plurality of vertical compartments are towed or floated to an erection site where they are filled with concrete or removable pillar members to form respectively, permanent or temporary columns for supporting drill platforms, piers, etc. First chains or weights are placed in one compartment of a casing to erect it without flooding, and then concrete or removable pillar sections are placed in a second compartment while compressed air is supplied through a third compartment underneath the casing to blow the sand on the bottom of the body of water away to permit the casing to embed itself in the floor of the body of water. Additional concrete or chains, for permanent and temporary columns, respectively, may be added to the several compartments, including that which contained the compressed air line, usually after the removal of the line therefrom, to anchor the column firmly in place.

Abstract: Liquefaction of a vapor such as carbon dioxide gas is achieved by utilizing the refrigeration available in liquefied natural gas (LNG) to sub-cool liquid carbon dioxide, which in turn is sprayed into carbon dioxide gas in a condensing vessel thereby liquefying the gas. Suitable control means are provided for maintaining a predetermined temperature within the condensing vessel and for regulating the flow rate of LNG in response to variations in the flow of liquid carbon dioxide before the sub-cooling of liquid CO.sub.2 by LNG is effected.

Abstract: A method and apparatus for transferring a liquefied gas from a first container into a second container without removal of vapor from the second container is disclosed.

Abstract: An ice maker control circuit for use with an ice maker of the type including an inclined refrigerated plate associated with means energized during an ice making cycle of operation to cause water to be continually circulated across the inclined plate as refrigerant is directed with respect thereto and wherein ice slabs built up on the plate are periodically released therefrom and directed to a cutting grid for separation into a plurality of cubes of ice; the control circuit including a bin ice accumulation switch responsive to a maximum build up of ice therein to terminate machine operation and an ice slab thickness control switch to selectively control circuit means for terminating the circulation of water over the plate and for initiating a hot gas defrost cycle of operation; the circuit further including a time delay thermal relay responsive to the bin ice accumulation switch sensing a maximum level of bin ice and operative to maintain an ice making cycle of operation until the ice slab reaches a desired th

Abstract: A piloted refrigerant valve for an air conditioning system to control refrigerant pressure within an evaporator to prevent frost accumulation on its exterior surfaces. The valve includes a disc-shaped hollow thermal sensor filled with water which solidifies and expands upon sensing the freezing temperature to cause a pilot valve to block a bleed port and thereby increase the fluid pressure above a reciprocally mounted piston valve. The pressure force produced on the piston valve moves it to a closed position to block refrigerant flow and resultantly to increase refrigerant pressure and temperature in the evaporator. After an initial start-up period of operation, the sensor maintains a position which locates the reciprocal piston valve so as to produce a substantially constant non-freezing temperature of refrigerant in the evaporator.

Abstract: The present invention provides an air conditioning system for a mobile home. The system includes securing a mounting means to the support structure of the mobile home and an air conditioning unit that is adapted to be removably secured to the mounting means. When installed on the mounting means, the air conditioning unit is aligned to deliver conditioned air into the interior of the mobile home through its built-in air distribution system.

Abstract: A cover for a freezer ice tray which prevents splashing out of the water in the tray before freezing, and additionally functions to maintain the tray in place in a freezing compartment of a refrigerator housed in a relatively unstable trailer or boat and to improve the heat conducting contact between the ice tray and the evaporator pipe. The cover has a downwardly directed front part along its entire width that substitutes as a door to the freezing compartment.

Abstract: A refrigeration plant of the absorption type in which the chilled surfaces of the absorber, condenser, and other coolers comprise water-sprinkled tube batteries, said batteries being arranged vertically and in parallel and having a common sprinkling system for distributing the water as a film on the outside of the tubes.

Abstract: A means for exchanging heat between two streams of a working fluid, during expansion and compression of said working fluid, thus providing heat removal from said working fluid either during expansion or compression and providing heat addition to said working fluid either during expansion or compression. The heat exchanger means may be either a finned wall, finned tubing, or heat pipes; also, other types of heat exchangers may be used. The heat exchangers are normally mounted within a centrifuge type rotor wherein said working fluid is either cooled or heated when said working fluid either expands or is being compressed within outward extending rotor passages.

Abstract: A lubricated joint assembly comprises joint means received in a boot having cuffs which allow coupling members to connect between the joint means and external mechanisms. The boot cooperates with the coupling members to fully enclose the joint means. The boot is pressurized with a lubricant charged thereto whereby the boot is expanded and compresses the lubricant therein. In the preferred embodiments, the lubricant is charged to the boot in a fashion which displaces all air from the boot, thus preventing oxidation of the lubricant. Further, in the present invention, the external shape of the expanded boot is controlled by controlling the shape of the boot before pressurization thereof and by also controlling the wall thickness of the boot in selected areas thereof.

Abstract: A straight knitting machine includes a plurality of sliding heads 1 driven around a guide track 2 by chain and sprocket means 3, 5. A plurality of holders 8 for yarn spools 9 are positioned above their associated sliding heads and are driven around guide tracks 10, 11 by chain and sprocket means 12, 14 coupled to the same drive shaft 15 as the chain and sprocket means 3, 5. Electrical connections for safety switches and thread delivery motors are made by sliding contacts on the heads 1 which engage stationary contacts on the straight portions of the guide path.

Abstract: A yarn supply device for a rectilinear knitting machine capable of supplying the needles of the machine with a predetermined quantity of yarn irrespective of the speed of operation of the machine. The supply device comprises a yarn feed unit incorporating a drive member such as a pulley around which the yarn is wound in order to obtain positive drive engagement, the pulley being driven by an electric motor energized with an error signal derived from the output signal of a transducer sensitive to the actual displacement speed of the yarn feed device, and a signal representing the desired speed derived from the displacement and speed of a cam bar and thrower bar of the knitting machine. Arrangements are made for compensation in the error signal for the different stretch in the yarn in dependence on the position of the thrower with respect to a fixed yarn guide, and also for the inertia of the drive member of the yarn feed unit.

Abstract: A container for liquids or solids carried in liquids has a rigid upper portion and a flexible lower portion. The rigid upper portion is mounted on and supported by a frame. The flexible lower portion is surrounded by a closed chamber which may, under certain circumstances also surround the rigid upper portion, whereby the contents of the container may be subjected to one or another of a variety of conditions such, for example, as being subjected to a vacuum or negative air pressure, a positive air pressure, a controlled atmosphere such as a selected gas, or a bath of treated liquid such as a washing solution. A wobble plate on the flexible lower portion is set in motion by an electric motor, the drive of which extends through the closed chamber of the flexible lower portion, thereby to agitate the contents under controlled conditions.

Abstract: A ski lock device for safely clamping a pair of skis in crossed relation to each other to prevent theft. The device includes a pair of clamps that fit about a first ski and over a second ski, with the second ski in crossed relation to the first. Each clamp consists of a pair of slotted members joined together by a threaded joint. A padlock clasp snaps through a hole in each clamp joint to lock the device in place.SUMMARY OF THE INVENTIONMy invention is a ski lock device for safely clamping a pair of skis in crossed relation to each other to prevent theft. The device includes a pair of clamps that fit about a first ski and over a second ski, with the second ski in crossed relation to the first. Each clamp consists of a pair of slotted members joined together by a threaded joint. A padlock clasp snaps through a hole in each clamp joint to lock the device in place.The device, in the locked position maintains a pair of skis in a crossed relation making an unwieldy package for a thief.

Abstract: A metal strip is spanned over a plurality of rollers carried on a pair of frames. A single heavy-duty drive motor rotates a common drive shaft that is connected via bevel gearing to the sun gears of a plurality of planetary-gear assemblies each having its planet carrier connected to the respective roller. The ring gear of one of these assemblies is fixed whereas the ring gears of all of the other assemblies are connected to respective compensating motors. A torque sensor at the output of each compensating motor generates an actual value signal indicating the amount of torque being applied by that motor to the respective ring gear. The comparator compares this actual-value signal with a set point coming from a single set-point generator and varies the motor speed in accordance with the difference between these two signals.

Abstract: Fluid forming apparatus having a constant-volume pressure cavity has oppositely movable rigid forming tool parts, each connected with a piston comprising a double acting cylinder mechanism. Forming pressure is developed by hydraulically forcing one tool part in the direction that tends to reduce cavity volume, thus, by reaction, forcing the other tool part in the opposite direction against restraint. A cam mechanism moving with said one tool part defines a pressure program. Sensor means, cooperating with the cam and with pressure regulating valve mechanism, controls pressure of the fluid driving said one tool part in accordance with the program and the position of that tool part.

Abstract: Spinning method for producing V-belt pulleys comprising the steps of preforming the grooves, decreasing the width of the grooves by compression and finally shaping the grooves. The spinning lathe comprises an eccentrically mounted and axially movable inner roller forming a back up roller for the shaping roller.

Abstract: A method and apparatus are provided for piercing metal members at high temperatures, particularly members containing slag inclusions, by the steps of urging said member, over a piercer point by rolling whereby said point passes through and forms an axial opening in the ingot, said point being formed of an alloy comprising 0.015% to 2% Carbon, about 5% to 65% Cobalt, about 15% to 35% Chromium and up to about 30% iron.

Abstract: Apparatus for manufacture of wire. The apparatus includes structure for drawing the wire through a conventional wire drawing device and including a pull roller at the output point thereof. The wire then travels through a zone wherein an electric current is caused to flow through said wire while same is in motion therethrough for heating and annealing same, after which the wire is cooled and then directed through a further die for further shaping and cold working of same. A pull roller is provided at the output end of the last-named die for pulling the wire therethrough. The wire is finally wound onto a spool. By heating the wire as noted, same can travel through the heating zone at the same speed as through the dies and hence the operation is continuous and does not require intermediate winding and unwinding. Suitable coupling structure is provided for effecting proper speed relationships between the peripheries of the first-mentioned and second-mentioned pull rollers.

Abstract: The invention contemplates low-cost and improved manufacture of an eccentric locking collar, as for use in securing a bearing ring or the like to a shaft. The locking collar is made by cold-forming a cylindrical metal blank with an eccentric cylindrical recess at one end and with a concentric cylindrical recess at the other end. A coining tool having the desired locking surface profile is inserted into the eccentric bore and is driven in axial compression causing blank material to flow or extrude around the profile. Thereafter, a punching operation completes definition of the concentric cylindrical bore which is ultimately to accommodate assembly to a shaft, and finishing steps are performed, such as set-screw adapting and tumbling.

Abstract: A fence dropper which may be used as a spacer or a post and which is suitable for supporting the wires of a wire fence, the fence dropper being provided with a series of tongues each of which is joined to but spaced from one edge of the body portion by a root. Each tongue is provided with a forwardly extending portion and a return portion which constitute with the body of the dropper a wire retaining aperture, but since the tongues are spaced from the dropper by their roots, the tongues form with the dropper edge slots in a plane which is at right angles to a fence, the arrangement then being such that a dropper may be positioned against a fence with wires in respective slots and rotated through 90.degree. whereupon the wires become contained within the wire retaining recesses.

Abstract: A tool for use in connecting two conductors by crimping a pre-insulated open-U shaped connecting device simultaneously around separate conductors is disclosed. The tool is adapted for trimming either or both wires and can attach the connecting device to a through wire so that a tap connection can be formed. The through wire extends out of the center of the connecting device and the tool forms the insulation around the through wire to establish a suitable dielectric.

Abstract: A system for measuring variations in floatability or floatation force of a loat under varying pressure conditions, including a liquid filled enclosure and means for varying the pressure therein, a dynamometric ring suspended in the enclosure with strain gauges located on each side of the ring, and means for suspending a test float and a ballast from the ring. The system may also include means for preventing inelastic deformation of the ring, and the strain gauges may be connected as adjacent arms of an electrical resistance bridge.

Abstract: A metallized ceramic substrate has a slot provided in one quandrant on one side thereof. The substrate is disposed in receiving means having either two or four restrictive openings therein and over which the substrate is disposed. Fluid pressure is supplied from a pressure source in a separate path to each of these openings. The opening, which has the slot disposed thereover, has a different pressure in its path from the pressure source than the other openings so that the location of the slot, if it is in the surface of the substrate disposed next to the openings, can be ascertained.

Abstract: A process for measuring, optimizing and controlling the gas permeability of a sinter mixture on a travelling grate by adjusting the flow of air and/or fuel to the furnace to maintain a zero pressure differential between the inside and the outside thereof such that all the gas generated permeates the sinter mixture, and determining the gas permeability as a function of said flows. These steps are repeated for various values of selected process parameters having a significant influence on gas permeability, one at a time, in order to determine the value of each parameter which produces optimum gas flow.

Abstract: The invention relates to a process and installation for detecting a fluid leak in a pipe sub-divided into sealable sections by a series of isolating valves arranged at each end of a section.As a result of this process and installation all normal pressure fluctuations occurring in the pipe can be followed without starting off the isolating valves but in the case of an accidental leak when the pressure drop exceeds the predetermined threshold value within a predetermined time, the isolating valves in the pipe are reliably actuated.

Abstract: Cigarettes are tested with air streams which are caused to pass lengthwise through the fillers while the cigarettes move sideways past a testing station. One or two stationary chambers for air at subatmospheric or superatmospheric pressure are mounted at the testing station so that the ends of cigarettes which are being tested extend into the chamber or chambers. The air pressure in the chamber or chambers equals or approximates the pressure of air streams at the respective ends of the wrappers of cigarettes so that air in the chamber or chambers prevents the streams from communicating with the atmosphere during testing. The streams are monitored for changes in pressure. Such changes are indicative of defects of cigarettes and signals which are produced during monitoring are used to segregate defective cigarettes from satisfactory cigarettes.

Abstract: A viscometer comprises a liquid feeding conduit opening into a measuring chamber and a capillary liquid outlet conduit connected to said chamber, pressure-sensitive means associated with said chamber for sensing the pressure variations in the latter, converting means for converting the pressure variations sensed by said pressure sensitive means into measurable and displayable quantities of value, said feeding and capillary conduits and said pressure-sensitive means being enclosed in a metallic block arranged in a heat-insulated space which includes heating means for heating said block, said heating means being adapted to maintain the temperature of said block at an adjustable predetermined value.

Abstract: A transducer arrangement for ultrasonic rail tester coupling carriages comprising a first pair of flat angle signal transducers that are both connected to be senders and receivers and are directed in opposite directions lengthwise forwardly and rearwardly of the rail along the center of the rail head, a second pair of flat angle signal transducers that are both connected to be senders and receivers and are directly forwardly and rearwardly of the rail but are canted toward the rail gauge edge at preferred angle of 19.degree., and a third pair of flat angle signal transducers, one of which is a sender and the other of which is a receiver, that are canted toward the rail gauge edge at an angle of 80 or more degrees to provide a zig-zag signal path of multiple bounces across the rail head. The transducers act through transmitting wedges made of a material to be inefficient as a medium through which ultrasonic sound may be sent such that a significantly improved signal to noise ratio results.

Abstract: It has previously been suggested to indicate, or record images of, internal inhomogeneities in a sample by means of an ultrasonic angle probe which is moved on the surface of the sample, the reflected echo signal being indicated as punctiform position markings in such a way that when added together the markings form an image of the projection of the inhomogeneities on the surface of the sample. It is now suggested that also the amplitudes of the echo signals are indicated, whereby much more information about the inhomogeneities is obtained. The amplitude can be indicated as a variation of the intensity, size and/or duration of the position markings. Another possibility is to indicate the amplitude by the length of a line segment.

Abstract: A fastener tension inspection system for use with torque producing power tools such as nut runners, screwdrivers, or the like. The inspection system includes a means for measuring torque or other tension proportional function applied to a fastener and a means for measuring at least one additional parameter associated with fastener tightening; for example, time or rotation. With appropriate electronic circuitry, the torquing cycle is started by freerunning the fastener and bringing it up to a predetermined low level of torque sufficient to seat the fastener. Upon reaching the predetermined low level of torque, the means for measuring the additional parameter is initiated and continues until final torquing is completed. The predetermined minimum torque level on the fastener must be reached and a predetermined maximum torque level not exceeded within a predetermined range of the additional parameter or the fastener is rejected.

Abstract: The nip pressure of a rotating roll is measured and displayed through the utilization of techniques which include the transmission and reception of electromagnetic radiation. A pressure transducer is mounted on the inner surface of a roll shell and connected through a bore of a roll shaft to a light transmitting circuit. The light transmitting circuit is mounted in a housing on the end of the shaft and includes a voltage/frequency converter connected to the pressure transducer for converting pressure indicative voltages to pulses. These pulses activate a lamp driver for energizing a lamp which is mounted for radiation along the axis of rotation. An electromagnetic radiation receiver, in the form of a phototransistor, converts the received radiation into an electrical signal which is displayed as a digital representation of nip pressure and/or as a voltage (pressure) profile on an oscilloscope.

Abstract: A test bench device is utilized for testing instruments used on road vehicles and the like, and permits testing to be carried out while the vehicle is in motion. The apparatus comprises in combination a plurality of pulse transmitter means, a first of which is positioned on the rear wheels of the vehicle, and a second of which is positioned on the gear-box drive of the vehicle, and a third of which is positioned to record movement of a tape means or the like which unwinds in accordance with movement of the vehicle along a test course. In a modification, the vehicle moves between two fixed exterior datum points defining a path along which the vehicle is moved to effect measurement.

Abstract: A method of calibrating a carburetor wherein air is flowed through the mixture conduit while air is also being delivered to the fuel bowl at a predetermined rate that equates to the actual fuel flow rate required to establish a desired air-fuel ratio and the metering rod is then positioned to equalize fuel bowl pressure with ambient pressure to thereby effect proper calibration to produce the desired air-fuel ratio.

Abstract: The engine of a motor vehicle is used to accelerate a flywheel up to a suitable test speed through rollers engaged with driven wheels of the vehicle. Then, when the wheels are braked, one torsion coupling gives a signal corresponding to the total braking force on both wheels and another torsion coupling between two of the rollers gives a signal corresponding to the braking force on one wheel. The braking force on the other wheel is obtained through a subtraction circuit. For testing undriven wheels, the flywheel is first brought up to speed by means of a set of driven wheels, then a clutch is released to free the flywheel while the rollers are stopped and the undriven wheel brought into position, after which the clutch is re-engaged and the undriven wheels are tested.