Section 29.—CUSHIONING.
For checking the impact of a blow, or more generally the momentum of a heavy moving part of a machine. The devices in use comprise (a) springs, see [Section 80]; (b) air cylinder, see [No. 1480]; (c) pistons driven by elastic fluids, such as steam and air, can be cushioned by imprisoning a portion of the fluid at each end of the cylinder; (d) brakes of various kinds, see [Section 5].
[519]. Hydraulic cushion. The descending ram, by its tapered end, closes gradually the discharge outlet for the water.
Hydraulic buffer stops are constructed on this principle.
[520]. Cushioning device, at the upper end of a steam-hammer cylinder. Should the piston pass the exhaust holes, the steam above is imprisoned, and checks the piston without shock.
Section 30.—DRILLING, BORING, &c.
Besides the ordinary tools in use, as gimlets, bradawls, pin and brace bits, augers, &c., which do not need description, the following are noteworthy:—
[521]. Is the ordinary V drill for metal work.
[522]. Flat point, or “bottoming” drill.
[523] & [524]. Countersinking drills for metal.
[525]. Centre bit for wood.
[526]. Twist bit for wood; clears its own borings. There is a variety with rounded cutter edges.
[527], [528], & [529]. Rock drills, or “jumpers.”
[530]. Earth borer, or mooring screw.
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[531]. Twist drill for metal.
[532] & [533]. Countersinking drills for wood.
[534]. Diamond drill for rock; bores an annular hole, the core of which breaks out at intervals.
[535] to [545]. Well boring tools for different kinds of strata; tools for raising broken rods, &c.
[546]. Hollow boring cutter for cutting a shoulder on a central core; dowelling bit.