Chapter LXXIV: Section 84: Toothed Gearing

=1515. Spur gearing.= For construction of teeth see text books.

=1516. Strongest form of spur teeth= for motion in one direction only.

=1517. Half shrouded spur teeth.=

=1518. Whole shrouded spur teeth.=

=1519. Double helical spur teeth,= stronger by 15 per cent. than straight teeth; work without backlash or noise, and may be half or whole shrouded; section of tooth on plane of motion is the same as the ordinary spur teeth (No. 1515).

=1520. Crown wheel and pinion.=

=1521. Long teeth spur wheels or “star” wheels.= Used on roller mangles, &c., where the centres rise and fall.

=1522. Plain bevil gear;= shafts at right angles.

=1523. Plain bevil gear;= shafts at acute angles.

=1524. Plain bevil gear;= shafts at obtuse angle.

=1525. Plain bevil gear;= four shafts at right angles.

=1526. Skew bevils;= shafts not in line with one another.

NOTE.--Where the pair are both of same diameter they are called “mitre
wheels.”

=1527. Spur wheel and pinion;= to increase or decrease power and speed the diameters can be varied to almost any proportion.

=1528. “Screw gear”;= single helical gear.

=1529. Skew spur wheels;= shafts not parallel.

=1530. Dr. Hooke’s gear.= Three or more separate wheels of similar or dissimilar pitch fixed together so as to divide the pitch and reduce backlash.

=1531. The same result obtained by two wheels,= one fixed to shaft, the other loose and forced round by a spring so as to follow the pitch of the pinion and destroy all backlash.

=1532. Mortise wheel teeth.=

=1533. Mortise wheel teeth;= another method.

NOTE.--Wood teeth are usually one-third thicker than the iron teeth
they gear into.

=1534. Pin wheel and pinion gear.=

=1535. Lantern wheel.=

=1536. Screw gear,= used in place of bevil gear. Shafts at right angles; teeth at an angle of 45°.

=1537. Variable speed cone gear.=

=1538. Variable speed square gear.=

=1539. Variable speed oval or elliptical gear.=

=1540. Irregular gear.=

=1541. Internal or epicycloidal gear.= See Nos. 550 and 1545.

Used for differential blocks, &c. Note that both wheel and pinion run
in the same direction, and that more teeth are in gear at one time
than with external gear as No. 1527.

=1542 & 1543. Varieties of “mangle” gear.= The pinion being revolved continuously in one direction produces a reciprocating motion of the wheel; the pinion shaft travels from inside the wheel to outside, and _vice versâ_, by rising and falling in the slot in the frame. See also No. 423.

=1544. Differential gear.= See Section 31. One wheel has one or more teeth more than the other; used for counters, &c.

=1545. Moore’s patent differential epicycloidal gear.= The pinion and wheel are loose on the shaft and eccentric. One wheel has one tooth more than the other.

=1546. Multiplying bevil gear.= ~A~ is a fixed wheel, the cross ~C~ is keyed to shaft, ~B~ loose on ditto, ~D~ and ~E~ loose on ~C~; then ~B~ is driven at a speed greater than the shaft in proportion to the diameters of the gear. See Patent No. 12,696, 1884.

=1547. Double worm gear,= right and left hand threads. Neutralises the end thrust on shaft. ~A~ and ~B~ may be geared together.

=1548. Pointed gear;= used for light work and for minimum of friction.

=1549. Curved worm gear,= for heavy strains. Several teeth are in gear at once, but the thread, having a varying section and pitch, is difficult to cut.

=1550. Antifriction worm gear= (Hawkins’). The wheel has four rollers; when one pair is nearly out of gear with the worm, the next pair is coming into gear. This worm is also difficult to cut.

=1551. Crown worm gear.=

=1552. Ball joint mitre gear.=

=1553. Multiplying rack gear.= The upper moving rack is driven at twice the speed of the spur wheel rod. The lower rack is fixed; used on planing and printing machines.

=1554 to 1557. Varieties of worm gear,= with straight, hollowed, and curved teeth; the latter are strongest.

=1558. Worm and rack gear.=

=1559. Differential worm gear.= The worm gears into two wheels, one having one tooth more than the other.

See also Sections 40 and 31.

Section 85.--TRANSMISSION OF POWER.

=a. By belt, chain, or rope.= See Sections 3, 66.

=b. By shafting.= See Section 76.

=c. By gearing.= See Sections 84 and 40.

=d. By steam or air= conveyed in pipes (elastic fluids).

=e. By water, glycerine, or oil= conveyed in pipes (non-elastic fluids).

=f. By stiff rods= running over guides.

=g. By wires or ropes= running over guide pulleys--wire rope transmission. See Section 66.

=h. By electricity= conveyed along wire conductors.