=711. Conical rotatory gear.= Applied to reaping machines. See also Pan
Screen, No. 1264.
=712. Triangular eccentric,= used to obtain a pause of one-third
revolution at each end of the stroke.
=713. Face plate worm gear.=
=714. Double rack and pinion gear.=
=715. Double gear wheels.=
[Illustration: 693.-715.]
=716. Eccentric gearing;= the wheel ~A~ being fixed on a crank pin in
the driving wheel ~B~, drives the dotted gear at a speed proportionate
to the diameters of the wheels ~A~ and the driven wheel.
=717 & 718. Forms of epicyclic or planet gear.= Several modes of driving
these may be employed by fixing one or other of the three wheels, the
other two revolving. See Differential Gear, Section 31.
=719. Multiple trammel gear.= The pinion is half the diameter of the
wheel, and makes two revolutions to one of the wheel.
=720. Trammel crank gear;= the crank revolves once to two double strokes
of the rod.
=721. Knight’s noiseless gearing,= for two shafts running in opposite
directions. Each shaft has two equal cranks at right angles, which are
coupled by links to rocking arms, which are also coupled in pairs.
=722. Eccentric variable speed toothed gear.=
=723. Scroll bevil gear.=
=724. Segment reversing gear,= to obtain two speeds in portions of one
revolution, and in opposite directions. See Reversing Gear, Section 74.
=725. Snail wheel,= or scroll ratchet.
=726. Combined spur and bevil wheel.=
=727. Double screw gear,= for steering gear, &c.
=728. Angular ball-jointed crank motion.=
=729. Crank gearing= between two shafts running in the same direction.
See No. 187. The cranks should be similar to Nos. 174 or 175.
=730. Snail worm gear.=
=731. Diagonal engine or pump,= with bevil gear revolving motion and
three or more cylinders.
=732. Angle coupling= on Dr. Hooke’s principle. See No. 292.
=733. Worm and crown gear.= Used in chaff machines; useful to obtain a
slow feed on two shafts in opposite directions.
[Illustration: 716.-733.]
=734. Ball wheel,= with limited angular traverse gearing into one or two
pinions.
=735. Scroll and rack.=
=736. Variable speed gear,= from an elliptical or other irregular-shaped
driving wheel, combined with a tied idle intermediate wheel.
=737. Spring friction grip wheels.=
=738. Intermittent reversible feed motion.= The pinion is of leather,
and drives the segment till it runs out of gear; when the machine is
reversed it travels an equal distance the opposite way.