1577. Radius bar and slot. The stud wheel can be shifted in or out of gear along the slot.
1578. Sliding back shaft, slides out of gear. See dotted lines.
1579. Method of throwing a pulley out of gear by slacking the belt. This is done either by a cam bearing or sliding motion to the driver shaft. Works best vertically. See also No. 1219.
1580. Cam slot motion for back shaft. To throw it in or out of gear.
1581. Motion employed for punching machines, &c. To set the punch in or out of action by a cam and hand lever.
Section 88.—VARIABLE MOTION AND VARIABLE POWER.
For variable speed and power by spur gear, see Sections 84 and 40.
For variable speed and power by bevil gear, see Section 84.
For variable speed and power by cam gear, see Section 9.
For variable speed and power by belt gear, see Section 3.
1582. Variable speed belt cones, for crossed belts. Angle of cones should not exceed 15°.
1583. Stepped cone gear.
1584. Variable throw crank pin. (See Hastie’s Patent, 3561, 1878; Knowelden and Edwards’, 2996, 1858.)
1585. Beam motion, with variable fulcrum to alter the proportionate lengths of stroke of driving and driven cylinders. See also No. 1606.
1586. Variable pressure accumulator. Both cylinders are in communication by a pipe, and the pressure varies with the angle between the rams.
1587. Wright’s variable gear. The radius of frictional contact of the wheels varies as they are moved closer together or separated.
1588. Olmsted’s variable cone friction gear, with intermediate double cone idle wheel instead of belt.
1589. Convex and concave cones for open belts.
1590. Three speed gear, each separate pair of spur gear being driven by its own belt pulley on separate sleeve pieces.
1591. Irregular or elliptical gear.
1592. Lever combination to obtain an even tension from a spring throughout its motion.
1593. Scroll spur gear.
1594. Scroll gear for obtaining a variable pull from a weight.
1595. Variable friction gear. The pinion can be moved up or down from the centre to the outside of disc to vary the speed.
1596. Owen’s compound lever variable pressure air pumps. The pressure increasing and speed decreasing as the pistons rise to the top of their stroke.
1597. 2-speed gear by one belt. One loose pulley B carries a transverse mitre wheel, which, gearing into the fixed mitre wheel A, drives the mitre wheel pulley C keyed to shaft at twice the speed of pulley B when the belt is on B; by shifting the belt to pulley C, the speed is 1 to 1. The third pulley is loose for running idle.
1598. 2-speed bevel gear with three wheels and sliding shaft, by which either pair can be put into gear.
1599. 2-speed bevel gear with four wheels and sliding shaft.
1600. Increasing speed cone and screw, friction gear. The cone is driven by frictional contact with the pinion.
1601. Variable fulcrum lever, with shifting pin and hole adjustment.
1602. Fusee barrel, as used in clocks and watches to equalise the tension of spring on the movement; may also be employed to give a variable speed. The spring is usually similar to No. 1484, and coiled in the upper barrel.
1603. Variable throw crank pin and slot, much used for variable feed motions in combination with some type of pawl and ratchet gear.
1604. Variable travel imparted to the piston rod from the crank by altering the point of attachment of the link A to the slot.
1605. Variable power pistons, single-acting.
1606. Effects the same ends as No. 1601 or 1585, by shifting the fulcrum point along the slot by means of a screw.
1607. Variable throw crank pin by means of a jointed crank and radial adjusting screw.
1608. Variable throw crank pin by attaching the crank pin to an eccentric disc. See Section 10.
1609. Wind motor-fan or turbine, with variable-angle vanes actuated by a central sleeve and cam or lever gear.
1610. Variable friction cone gear; the small friction pinion can be moved radially to and fro to alter the leverage and consequently speed of driving radius from the cone.
In the steam engine, compressed air engine, and gas engine (these being all elastic fluids), the power given out is varied by altering the supply of steam, air, or gas. In the water wheel the power may be varied by altering the quantity of water (or head of water) supplied to the wheel. In the turbine the power can be varied by altering the head of supply water and the angle of vanes; altering the quantity reduces the speed and efficiency. The turbine will not work well under great variations of either head or quantity.
See also Nos. 736, 722, 723, 1190, 1191, 381, 382, 384, 385, 377, 372, 373; and Sections 20 and 40.
For variable pressure or tension by springs, see Section 80.
Variable balance weights, Section 20.
Section 89.—VALVES AND COCKS.
Of the almost innumerable varieties of valves and cocks in use the following are selected as types without reference to special uses, each type having its peculiar value, and the drawings are only intended to indicate the special features of each type without such details as may be varied to suit each particular requirement or application.
1611. The common plug cock.
1612. The same, but with screwed gland.
1613. 2-way or 3-way plug cock, with packed gland.
1614. Hollow plug blow-off cock, with packed gland.
1615. Back pressure or check valve, self closing.
1616. Ball valve and guard, self closing.
1617. Indiarubber disc and grating valve.
1618. Double flap indiarubber or leather and grating valve.
1619. Simple flap valve faced with rubber or leather.
1620. Rocking or rolling valve. For opening and closing gradually and easily against pressure.
1621. Roll-up valve. For same purposes as the last named.
1622. Sector full-way screw down valve, shown closed; when open the disc is up in the chamber out of the waterway.
1623. Double face valve; the spindle is screwed into the stuffing-box neck and the lower valve, the upper one being pinned to the spindle; the thread in the lower valve is twice the pitch of the upper thread.
1624 & 1625. Spring relief valves; the springs are adjusted to blow off at any stated pressure, which may be regulated by a screw or nut (not shown).
1626. Weighted lever relief valve or safety valve.
1627. Reducing valve, can be adjusted by the balance weight to pass fluids from a high pressure to any lower pressure.
1628. Another form, with spring balance adjustment and equilibrium valve.
1629. Equilibrium valve.
1630. Equilibrium valve, not steam tight, but serrated, to cut off gradually, employed for governors of steam engines.
1631. Equilibrium cylindrical grating valve, may be used to open and close either by vertical or revolving motion.
1632. Common throttle or butterfly valve.
1633. Duplex throttle or damper for a three-way pipe or flue.
1634. Hydraulic high-pressure check valve, with long guide wings.
1635. Hydraulic plug or spindle valve and seating; all seatings for high pressure should be narrow and hard.
1636. Duplex or Ramsbottom safety valve; each valve serves as a fulcrum by which to lift the other. One fulcrum point should be jointed to the lever and the latter move in a vertical guide, or else the point of attachment of the spring to the lever be placed below the level of the valve seatings.
1637. A modification of the last named.
1638. Pass valve, used for pneumatic despatch tubes.
1639. Oscillating lever duplex valve.
1640. Simple radial disc valve or sluice.
1641 & 1642. Oscillating cylindrical valves. Corliss valves; sometimes made tapered or conical.
1643. Multiple ball valve, for high lift delivery valve of large pumping engines. Balls are of guttapercha, and open and close without shock.
1644. Multiple ring valve. The rings open and close in succession, thus avoiding shocks.
1645. Double beat ring valve.
1646. Double beat equilibrium or Cornish valve. The upper seating can be made of such area as to partly or entirely balance the valve.
1647. Multiple ring valve. The indiarubber rings expand and contract over the perforations.
1648. Double-beat valve, with sunk seating.
1649. Common D slide valve, with three ports.
1650. Duplex or double D slide.
1651. Another form, partly in equilibrium.
1652. Equilibrium slide valve, with circular packed trunk on back, of area sufficient to balance the face area of valve.
1653. Similar result obtained by a piston and link.
1654. Equilibrium piston valve employed in lieu of the slide valve. A steam pipe, B B exhaust.
1655. Gridiron slide valve.
1656. Common plate slide valve or sluice, used for blast pipes.
1657. Floating ball valve, for automatic discharge of air from water mains.
1658. Ordinary double-faced sluice valve, lifts clear of the water way.
1659. Single face sluice valve, for sewage water, &c.
1660. Flap sluice valve. Tidal outlet valve.
1661. Diaphragm valve.
1662. Oscillating disc valve, for gas.
1663. Large 3 or 4-way plug cock.
1664. Finger valve, closed by a spring.
1665. Taper cone valve, for gradually closing an outlet.
1666. Dome valve, used for hot blast, hot gases, &c. This form retains its shape when heated, expanding evenly.
1667. Common floating ball tap.
1668. Three-way air valve.
1669. Duplex slide, used to close a number of openings at once.
1670. West’s spiral valve, with indiarubber cord which expands and contracts over a spiral perforated groove.
1671. Dennis’ self-lifting valve. The valve is kept to its seat by the pressure being admitted on to its back through small hole A; when the larger hole B is opened by the spindle the back pressure is relieved and the valve lifted by the pressure below its conical underside.
1672. Common cone plug.
1673. Equilibrium plug or cylindrical valve, double ported.
1674. Another form of self-lifting valve. See No. 1671 for description.
1675. Compound flap valve.
1676. Indiarubber pump valve.
1677. Venetian shutter or compound butterfly valve.
1678. Bye pass used to allow a small flow when the main valve is shut off. Used also to equalise pressure on both sides of a large valve to enable it to open easily.
1679. Bell and hopper, or cup and cone; used for blast furnaces, coke ovens, and gas generators.
1680. Cup valve and suspended weight.
1681. Four-way valve for hot water pipes, &c.
1682. Oscillating valve.
1683. Gas purifier centre valve, for four purifiers; to work one purifier off and three on, or all four on at once. It is similar in plan to No. 1684, but has an additional top valve which allows the gas to pass into the fourth purifier; the top valve has an independent sleeve and lever motion.
1684. Gas purifier centre valve, employed to deliver and discharge gas into and out of any one, two, or three out of four purifiers. The motion of the gas is shown by the arrows.
1685. Conical grating valve with radial slots, opened or closed by revolving motion.
Section 90.—WATER WHEELS AND TURBINES.
1686. Simple undershot wheel.
1687. Breast wheel.
1688. High breast wheel.
1689. Overshot wheel.
1690. Return overshot wheel.
1691. Internal feed re-action wheel.
1692. Sunk wheel, driven by air: may be used as a meter for gas or air.
1693. Current wheel, driven by tidal or river current.
1694. Flutter wheel, with high fall.
1695. Horizontal wheel.
1696. Re-action wheel, the oldest form of turbine.
1697. Engel’s diagonal wheel.
1698. Scoop wheel for raising water. See also No. 1024.
1699. Wheel, with internal buckets and feed.
Note that most of these may be reversed and made into water raising machines, as No. 1698.
1700 to 1703. Sections of various forms of buckets in wood and iron. No. 1703 is a ventilated bucket which allows air to escape as the water enters.
For governing speed of water wheels and turbines, see Section 41.
1704. Fourneyron’s turbine, outward flow; the outer vanes are fixed, the inner ones revolve with the shaft.
1705. Jonval’s turbine, downward flow; either the upper or lower set is fixed.
1706. Swain’s turbine, inward and downward flow, with inward curved vanes or flumes.
1707. Leffel’s turbine, inward and downward flow; has one outer ring of fixed vanes and two inner sets revolving, but having different angles of flow.
1708. Undershot jet wheel for high pressure water.
Many other forms of turbines are extant, but are mostly modifications of the above types. The best types have means of varying the angle of the vanes and areas of passages to suit varying quantities of water.
Section 91.—WHEELS IN SEGMENTS.
1709. Heavy gearing for rolling mills, &c., with dovetailed joints wedged and packed.
1710. Wheel cast in sectors bolted together.
1711. Bevil wheel in halves.
1712. Wheel with rim in segments bolted together, and provided with bored and cottered sockets for arms in both rim and boss.
1713. Fly wheel rim, cottered and dowelled together.
1714. Arms and boss cast in one: the rim in segments, bolted together and to the arms.
1715. Tension wheel. The tie spokes are sometimes arranged in two sets at a slight angle to each other to prevent the rim turning without the boss. Bicycle wheels are of this class.
1716. Wrought-iron wheel, with cast boss.
1717. Wrought-iron wheel, with cast boss.
1718. Rim in segments bolted together, wood arms and cast boss, with sockets to receive arms; this type is much used for water wheels.