V-Belt
A leather or fabric belt of blunt V-section, adapted to run upon pulleys with V-shaped grooves. The belt is either notched upon its working face or built up of overlapped layers of leather to give it flexibility. Such a belt may be run quite loose without serious slipping and is sometimes used to drive radiator fans.
Synonym: Trapezoidal belt.
V-Type Motor
See motor, V-type.
Valve
Any device for controlling the flow of a fluid through a passage, such as a pipe, or through an opening from one chamber to another, consisting of means for opening or closing such passage or for enlarging or contracting its cross section at will, as, for instance, by the insertion into or withdrawal from it of a movable member, such, for instance, as a slide or damper or by the seating or unseating of a tightly fitting part in the entrance or exit space of the passage. The entrance and exit of the working fluid from the cylinders of gas and steam engines is affected through valves, automatically opened and closed by the engine mechanism and most of the definitions here given refer to engine valves, although valves are also used in fuel systems, lubrication systems, etc.
Valve, Admission
See inlet valve.
Valve, Automatic
Specifically, a valve, usually of the poppet type (see valve, poppet), which is opened automatically by the difference in pressure of the fluid acting upon the two sides of its disc and which is closed by a spring. Such valves were formerly used as gas engine inlet valves opening inwardly by atmospheric pressure, and admitting the fuel charge to the cylinder when the rarefaction therein, caused by piston movement, became sufficient to overcome the closing spring pressure. Such valves are used as the crank case inlet valves of two cycle engines (two port type) (q. v.) and as the auxiliary air valves (q. v.) of carburetors and similar ones, as suction valves of air, oil and gasoline pumps and water feed pumps.
The term is used in contradistinction to mechanically operated valve. Synonym: Suction operated valve, clack valve.
Valve, Caged
In gas engine practice, a valve usually of the poppet type, which, together with its seat, its spring and the valve stem guide, can be removed from the cylinder in which it is used. Such valves are used in overhead valve gas motors (see valve, overhead), the cage usually being cylindrical, provided with a gas passage by which it connects with the manifold, and arranged to be screwed into a threaded hole or clamped in an unthreaded hole in the cylinder head, seating gas-tight upon an annular gasket (q. v.). Valve, Concentric A combination of two valves arranged concentrically, so that intake and exhaust can take place through the same cylinder port and space thus be economized so that valve openings of large area as compared to the cylinder bore can be secured. In one form, which has been used in an air-cooled motor, the intake valve is hollow and annular and its external edge closes upon a seat formed in the cylinder head, and the exhaust valve is an ordinary poppet valve, coaxial with the inlet valve and within it, seating upon the internal periphery of the head of the latter. Both valves are lifted as a unit during intake and the exhaust valve only during exhaust.
Valve, Distributor
A valve, usually rotary in its action, the function of which is to control the flow of fluid from a common source of supply to several points of delivery in regular succession. Such valves are used to distribute the fuel charge from the carburetor to the pump chambers and working cylinders of two cycle motor, distributor valve type); to deliver oil to a series of leads; in self-starters (q. v.) of the spark type to distribute acetylene gas to the motor cylinders, and in self-starters (q. v.) of the gas pressure type to furnish gas pressure to the motor cylinders in their firing order. In the latter application the distributor valve consists of a rotating disc, provided with an arc shaped port, operated at one-half crankshaft speed (for a four cycle motor), which disc contacts with and moves over a flat surface in which equally spaced holes deliver the gas from the gas-tight valve housing through tubes to the several cylinders.
Valve, Exhaust
See exhaust valve.
Valve, Inclined
A gas engine valve of the poppet type, the axis of which makes an acute angle with the cylinder axis. Overhead valves are often so placed, as very large valve diameters and a domed form of cylinder head may be employed when the valves are so placed.
Valve, Inlet
See inlet valve.
Valve, Interchangeable
A gas engine poppet valve which can be used either as an exhaust or inlet valve in any particular engine. The valves of the two sets being identical, one spare valve serves to replace any one of the valves of the engine which may have broken.
Valve, Mechanically Operated
A valve which is operated by power driven mechanism and not by suction or manually. Specifically, a gas engine valve which is operated by mechanism driven by the motor of which it is a part, in contradistinction to an automatic valve (see valve, automatic). The valves of practically all gas engines are mechanically operated. (See valve gear.)
Valve, Mushroom
See valve, poppet.
Valve, Needle
See needle valve and carburetor needle valve.
Valve, One Piece
A gas engine poppet valve, the head and stem of which are integral, being a single forging, in contradistinction to a valve whose head and stem are separate parts screwed together or united by welding the more usual practice.
Valve, Overhead
A gas engine valve, generally of the caged type (see valve, caged), which is placed directly in the cylinder head, in contradistinction to one which is located in a pocket or valve chamber communicating with the cylinder (see valve pocket), and which thus permits gases to enter or leave the cylinder directly, avoiding the friction and transfers of heat incident to their movement through any intervening passages. Such valves are practically universally used upon air cooled motors. For method of operation see camshaft, overhead; push rod and rocker arm.
Synonym: Valve in the head.
Valve, Piston
A type of gas engine valve, consisting of a piston, similar to a motor piston, which fits in and is caused to reciprocate (q. v.) in a cylinder (the valve cylinder) in the wall of which is a port communicating with the working cylinder (the exhaust or inlet port, q. v.). When the valve piston is so moved by the valve gear (q. v.) that its end begins to pass off from this port, gases may pass therethrough to or from the valve cylinder and out of or into the working cylinder, and when the end of the valve piston has again covered the port, gas movement is prevented. Instead of employing the end of the valve piston to effect the valve action, a port may be cut in the piston wall, which permits gas flow when it registers with the port in the valve cylinder. Piston valves have lately been applied to four cycle gas motors in order to secure silence of operation and improved filling and evacuation of the cylinders, a separate valve generally being used for exhaust and intake. Such valves are sometimes used in steam vehicle motors.
Valve, Pocketed
A gas engine valve, especially a poppet valve, which is located in a chamber or pocket (see valve pocket) attached to and communicating with the working cylinder, in contradistinction to one which is located directly in the cylinder wall. (See valve, overhead.)
Valve, Poppet
A disc valve, borne upon a guided stem and having a reciprocating motion in the line of its axis. When closed, the edge of its disc or head rests, fluid-tight, upon an annular seat formed in a partition which separates a chamber from which fluid is to be transferred from a chamber into which it is to be transferred. In opening, the valve moves away from its seat and the fluid flows through the passage formed between its head and its seat. This is the type most generally used for gas engine inlet and exhaust valves, being generally mechanically opened by cam action and closed by a spring. See valve, mechanically operated; valve head, valve stem, and valve spring.
Synonym: Mushroom valve, miter valve.
Valve, Poppet (Flat Seated)
A poppet valve the seating surface of the head of which is flat or in a plane at right angles to its axis and contacts with an annular seat which is also flat or in a plane at right angles to the valve axis.
Valve, Poppet (Taper Seated)
A poppet valve, the seating surface of the head of which is beveled or conical and which contacts with an annular seat which is correspondingly beveled or conical. The angle of the conical surfaces of head and seat is usually about 45 degrees with the plane of the head. The most commonly used type of gas engine poppet valve.
Synonym: Conical seated valve, bevel seated valve.
Valve, Rotary
A valve which is rotated upon a shaft and in so rotating alternately permits and cuts off the flow of a fluid, the valve being pierced with a passage which, when it registers with the inlet or exit passages provided for the fluid, allows the flow thereof. Such valves as applied to four cycle gas engines, in order to secure quiet action and complete filling and evacuation of the cylinders, are of various forms, mechanically operated by gearing. In one type the single valve employed is a disc on a vertical shaft operated at one-half engine speed, seated against the inside of the cylinder head and pierced with a sector shaped opening which alternately registers with the exhaust and inlet ports cut in the cylinder head. In another type the single valve is a cylinder rotated at one-quarter engine speed, in a cylindrical housing formed upon the cylinder head. The valve is pierced by a diametral passage, each end of which registers alternately with the inlet and exhaust ports cut from the housing into the cylinder. Instead of a single valve, separate valves may be used for inlet and exhaust, each valve consisting of a hollow cylinder with a port in its wall, fitting in a housing formed in the cylinder head. When the port registers with a port cut in the cylinder wall, gas movement is permitted, the hollow valve acting as a gas passage.
Valve, Slide
See slide valve.
Valve, Sliding Sleeve
A type of gas engine valve, consisting of a thin cylindrical sleeve, or a pair of concentrically arranged sleeves, fitted between the cylinder wall and the piston and pierced with ports which control the transfer of gases to and from the cylinder through ports in its wall, the sleeve or sleeves being reciprocated parallel to the cylinder axis or given a combined reciprocatory and rotary motion by suitable valve gear. In the Silent Knight sliding sleeve motor two concentric sleeves are employed, which are independently reciprocated by two crank and connecting rod mechanisms at a frequency one-half that of the piston. The inlet and exhaust ports in the cylinder wall are at opposite sides thereof, above piston travel (q. v.), and each extends about one-third around the cylinder. Each side of each sleeve is pierced toward its inward end with a correspondingly arranged port, and the reciprocatory motions of the two sleeves are so timed that, during intake, the intake ports of both sleeves simultaneously register with the intake port in the cylinder wall and the charge enters, while, during exhaust, the exhaust ports in both sleeves simultaneously register with the exhaust port in the cylinder wall. At all other periods in the cycle the sleeves prevent gas movement. In this construction the rate of valve opening is high, the area of the passages is large, and their resistance is slight; there are no valve pockets to add to the surface exposed to the charge, and the valve action is quiet and capable of permanent adjustment.
Valve Cap
A plug which screws into a valve pocket (q. v.) and closes the same, the removal of which permits the withdrawal of the poppet valve which is located therein. The cap usually seats upon a ring-shaped gasket, and a spark plug is commonly located in a hole drilled and tapped in the cap.
Synonym: Valve plug.
Valve Chamber
See valve pocket. Valve Clearance See clearance.
Valve Cover Plate
A readily detachable plate used to protect poppet valve gears from dust and to retain lubricant upon the parts. (See valve gear, enclosed.)
Valve Diameter
The diameter of the passage in which a poppet valve is seated. It is usually the same as the smaller diameter of the head of a conical or taper poppet valve.
Synonym: Clear valve diameter.
Valve Gear
The term applied to all the mechanism concerned in operating engine valves. In gas engines of the poppet valve type, it includes the cam mechanism, push rods, rocker arms, valve springs, valve guides, etc.; and in rotary valve, piston valve and sliding sleeve gas motors it includes the gears, shafts, cranks, connecting rods, rockers, etc. In steam engines it includes the eccentrics, eccentric rods, valve stems, etc.
Valve Gear, Enclosed
A valve gear in which the parts that operate outside of the engine structure, such as the valve stems, push rods, valve springs, etc., of a poppet valve gas engine, are protected from dust and so housed as to be susceptible of continuous lubrication, by some such device as a tightly fitted plate covering them in and bolted to suitable projections cast upon the outsides of the cylinders.
Synonym: Valve gear housing.
Valve Grinding S
ee grind.
Valve Grinding Tool
A tool similar to a bit stock, provided with a screwdriver-like point adapted to rotate a poppet valve upon its seat in the process of grinding the same, and to facilitate the occasional separation of the valve from its seat to cause the redistribution- of the grinding material thereupon.
Synonym: Valve grinder.
Valve Head
The disc-like portion of a poppet valve (see valve, poppet) which performs the valve function. It is usually made of nickel steel (see steel, nickel) or of cast iron, and is slightly convex on its outward surface and concaved upon its inner surface to form a fillet (q. v.). The stem (see valve stem) is either electrically welded into an axial hole therein or is screwed and riveted thereinto. Its outer surface is slotted to receive a screwdriver point.
Valve Housing
Any stationary part which encloses a valve. In gas engines it may be an integral part of the cylinder or a part attached thereto. It usually forms a gas passage to or from the valve, a pipe branch from a manifold being connected to it.
Valve Lap
See lap.
Valve Lead
See lead.
Valve Lift
The distance through which a poppet valve moves in passing from its closed to its full open position.
Valve Lifter
See pushrod.
Valve Location
The positions occupied by the valves of a gas engine with reference to the working cylinder. Poppet valves may be located in pockets at the sides of the head (see valve, pocketed). Both inlet and exhaust valve may be so placed, side by side, or one over the other on the same side of the cylinder (see cylinder, L type), or the inlet valve may be pocketed upon one side of the cylinder and the exhaust valve upon the opposite side (see cylinder, T type). One valve may be pocketed upon one side of the cylinder and the other valve may be in the cylinder head (see valve, overhead). Both valves may be located in the head (see valve, overhead) with their stems parallel to the cylinder axis; inclined thereto (see valve, inclined) or in the side of the head with their stems perpendicular to the cylinder axis.
Synonym: Valve position, valve arrangement.
Valve Plunger
See push rod.
Valve Pocket
A chamber, usually cast integral with the cylinder head of a gas engine upon the side thereof, communicating with the cylinder and with the inlet or exhaust piping, respectively, through ports, with a valve, usually of the poppet type, seated in a dividing partition within the pocket. Access to the pocket is secured by removing a valve cap (q. v.).
Synonym: Valve chamber, valve housing.
Valve Seat
The surface with which a valve is in contact when closed and upon which it forms a fluid-tight joint. The seat is usually finished by grinding the valve upon it. The seats of gas engine poppet valves are annular, with flat or conical surfaces (see valve, poppet), and are formed in the metal of the valve pocket (q. v.), or of a valve cage (see valve, caged),
Valve Setting
See valve timing.
Valve Spring
The spring which returns a valve to position. The springs used with gas engine poppet valves are usually of the spiral type, wound of high carbon or vanadium steel wire, threaded around the valve stem (q. v.) and compressed between the end of the valve stem guide (q. v.) and the valve spring washer (q. v.) and valve spring key (q. v.). They act to promptly close the valve upon its seat after it has been opened by the push rod (q. v.) or rocker arm (q. v.)- A light spiral spring is sometimes used in a poppet valve operating mechanism to keep the push rod in constant contact with its cam, and thus avoid the tapping noise otherwise caused by the hamming like action of these parts.
Valve Spring, Shear Type
A type of valve spring (q. v.) consisting of a loop of wire with spiral convolutions at its closed end, the free ends of which act respectively upon a fulcrum and upon a valve to close it. Springs of this type stand further away from the hot parts of the motor than spiral springs, and, being thus less likely to lose their temper by heat, are used upon some air cooled motors.
Valve Spring Key
A pin which is passed through and secured in a hole drilled in a poppet valve stem, the function of which is to resist the reaction of one end of the valve spring (q. v.) and to hold it in place.
Valve Spring Remover
A tool, consisting of a lever, adapted to be adjustably fulcrum upon some part of a motor, the short arm of which is engaged under the valve spring washer (q. v.) and the long arm moved by the hand, compressing the valve spring away from the valve spring key (q. v.).
Valve Spring Washer
A cup shaped washer which is threaded upon a poppet valve stem and receives the end of the valve spring, and which is held in place by the valve spring key (q. v.).
Valve Stem
The rod-like part of a gas engine poppet valve (see valve, poppet), to which is axially attached the valve head (q. v.), and which guides the motion of the valve. It is usually made of carbon steel rod and its free end is case hardened (q. v.) to resist the wear of the push rod or rocker arm impact, and near this end is drilled a hole for the reception of the valve spring key (q. v.). In a steam vehicle motor, the rod which operates the slide valve (q. v.) from the eccentric rod (q. v.) and eccentric (q. v.).
Valve Stem Guide
The specially formed part of a valve pocket (q. v.) or of a valve cage (see valve, caged), in which is drilled a hole, coaxial with the valve seat, in which slides the stem of a poppet valve, and by which its motion is guided. The hole is usually provided with a replaceable bushing (q. v., the valve guide bushing). One end of the valve spring acts against the external end of the valve stem guide.
Valve Timing
The adjustment of the valves of an engine so as to open and close at such periods in its cycle as to give the best operative results, such as maximum output or maximum fuel efficiency. See lap; lead; cut-off, point of. For approximate periods of opening and closing of gas engine poppet valves, see exhaust valve and inlet valve. The timing of such valves is primarily dependent upon the form and angular relations of their cams (q. v.) and by the mesh of the camshaft gears (q. v.), but is influenced by the adjustment of the push rods (q. v.).
Synonym: Valve setting.
Valve Tool Fulcrum
A small projection or ledge, cast upon the outside surface of a gas motor cylinder in such a position as to form a convenient fulcrum for the lever of a valve spring remover (q. v.).
Vanadium Steel
See steel, vanadium.
Vaporization
In general, the change of a liquid into an vermiform or vaporous state (vapor), brought about by the application of heat and facilitated by the reduction of the pressure which acts upon the liquid. This change of state involves the absorption of a large amount of heat (latent heat of vaporization). In automobile practice, that form of vaporization known as evaporation, or the change of a liquid into a vapor at the liquid’s surface, at ordinary air temperatures, is of chief interest. All internal combustion vehicle motors make use of gaseous fuel consisting of suitably proportioned mixtures of air and the vapor of some volatile combustible liquid, which are produced by evaporation in a carburetor (q. v.), and all steam vehicle boilers, which are fired with liquid fuel, make use of similar mixtures formed in a vaporizer (q. v.) and mixing tube (q. v.). Gasoline (q. v.), denatured alcohol (q. v.), benzol (q. v.), evaporate at ordinary temperatures, and are thus available for the formation of fuel mixtures, little -or no application of artificial heat being required, the evaporation of such fuels in carburetors which are unjacketed being accomplished by the heat in the air and liquid used, and in carburetors, exhaust jacketed (q. v.), and in carburetors, water jacketed (q. v.) partly by heat artificially applied. In all carburetors evaporation is facilitated by the reduced pressure acting therein caused by the engine suction, by the rapid removal of the vapor from the liquid surfaces by the moving air, and by the practice of finely dividing the liquid at the spraying nozzle (see carburetor, atomizing), so that a very large liquid surface is exposed to the passing air. Synonym: Gasification, evaporation.
Vaporizer
In a steam vehicle burner (q. v.), an arrangement of piping through which the liquid fuel is passed, and which is exposed to heat, for instance, by being placed across the face of the burner plate (q. v.), so that the fuel may be warmed and may readily vaporize when it is sprayed into the mixing tube (q. v.) at the burner jet (q. v.). The pilot light (q. v.) is usually so placed as to keep the vaporizer warm when the main burner is shut off. The term vaporizer is sometimes applied to the carburetor (q. v.).
Vaporizing Chamber
See mixing chamber.
Vaporizing Tube Carburetor
See carburetor, vaporizing tube.
Ventilator
An arrangement for admitting air for purposes of ventilation into the body of a closed car or of a car of the fore-door type (see body, fore-door), consisting of an adjustable slide or register closing or uncovering perforations in the body, doors or dash or a deflector plate and orifices answering the same purpose, by the adjustment of which more or less air can be admitted to the body or to the front seat compartment.
Venturi Tube
A tube for the flow of fluids, of somewhat hour-glass shape, which may be considered as formed by the junction at their smaller ends, of two tubes, each of which is the frustum of a circular cone, the junction where the cross section is the least being known as the throat or waist. The mixing chambers (q. v.) of carburetors are quite often Venturi tubes, as this design secures a very decided increase of suction at the spraying nozzle (see carburetor spraying nozzle), which is located at the throat, and hence a very energetic action thereof and a tendency toward homogeneity of mixture, without excessive contraction of the air flow through the mixing chamber, the effect of the flared outlet of the Venturi, being to facilitate the delivery of air. A large gas output, together with low frictional resistance, is thus secured.
Vibrator
See magnetic vibrator.
Vibrator Coil
See coil, vibrator.
Viscosity
That property of a liquid dependent upon the degree of cohesion among its particles, in virture of which it is sluggish in its flow. The term is chiefly used in reference to lubricating oils, oils of considerable viscosity being better suited to the maintenance of continuous lubricating films between surfaces acting under heavy pressures than those of slight viscosity, but giving rise to increased liquid friction. Viscosity is increased by reduction of temperature (see cold test). It is measured by the viscometer, the indications of which depend upon the weight of liquid which is discharged in a given period of time at a given temperature and constant known head through a small tube of standard area. The opposite of fluidity.
Synonym: Body (q. v.).
Visor
A forwardly and downwardly sloping extension formed upon the forward ends of a front fender (q. v.), shaped like a cap visor and designed to catch the road splash from the front wheel.
Volt
The practical unit of electromotive force (q. v.). That electromotive force which, steadily applied in a closed electric circuit of a total resistance of one ohm (q. v.), causes a current of one ampere to flow therein is one volt.
Voltage
Electromotive force expressed in volts.
Voltammeter
An electrical measuring instrument, consisting of a voltmeter (q. v.) and ammeter (q. v.) combined, for convenience, in the same case.
Voltmeter
An instrument, similar in most respects to an ammeter (q. v.), but used for the measurement of electromotive force and giving indications expressed in volts. The wire coil of a voltmeter is of extremely high resistance (q. v.), and thus the current which flows through it is practically proportional to the electromotive force applied to it. The electromagnetic effect which moves the pointer, being proportional to the current flowing in the coil, the indications of the instrument are proportional to the electromotive force being measured.
Volumetric Efficiency
See charge ratio.
Vulcanization
A process for rendering rubber more highly elastic, stronger, more durable and less liable to the attacks of solvents, by adding to it a carefully proportioned amount of sulphur and “curing” it, usually under pressure, for a short time, at a temperature of about 300 Fahr. The rubber of vehicle tires is all vulcanized more or less highly, dependent upon the character of the service required of it. Vulcanization is employed to affect the permanent adhesion of the fabric and rubber layers of pneumatic tire casings, and in joining to the tire structure the rubber or rubberized fabric used in making repairs (v.): To vulcanize.
Vulcanizer
The apparatus in which vulcanization is effected. In this connection, the apparatus employed to perform the vulcanization required in the repair of pneumatic tire casings and inner tubes, consisting of an iron mold or plate fitting around or upon the portion of the tire to be repaired, and means for clamping the mold or plate thereon and for applying heat from the mold to the rubber to be vulcanized. Such vulcanizers may be stationary and capable of making extensive repairs quickly, or portable and intended for smaller repairs, which may be performed, if desired, without removing the tire from the wheel.
Vulcanizer, Electric
A type of vulcanizer in which the heat required is developed electrically in conductors embedded in the metal of the iron or aluminum plate or mold. The temperature of the vulcanizing surfaces is indicated by a thermometer, and is automatically maintained at the correct point by means of a thermostat (q. v.) within the apparatus, which interrupts the heating current when the proper temperature is exceeded and re-establishes it when the temperature is too low. In some vulcanizers a rheostat (q. v.) is adjusted by hand to maintain the required current strength and temperature. Portable vulcanizers of this type, which may be operated in connection with any commercial electric circuit, are provided with means for clamping the vulcanizing surfaces to the tire, even though it is still upon its wheel, and the surfaces are so formed as to enable repairs upon both casings and inner tubes to be accomplished.
Vulcanizer, Steam
A vulcanizer, the molds or plates of which are set into the external surface of a closed chamber containing water, to which the heat from a gas, gasoline or alcohol flame is applied to raise steam, which brings the vulcanizing surfaces to the required temperature, a steam gauge or thermometer being used to measure the same. Such vulcanizers may be stationary or portable, the latter type usually burning alcohol and being adapted to the repairing of tires on or off their wheels.
Vulcanizing Cement
A rubber cement used in making tire repairs which are to be vulcanized.
Vulcanizing Rubber
Rubber compounded with sulphur and capable of vulcanization.
