Page 234 - The Tribology Handbook

Pistons B16

HYDRAULIC PISTONS

Type A-Semi-static operation
(pressure unidirectional)

Piston may be made from aluminium or cast iron. Opera-
tion may be by a push rod or a piston rod bolted through
the pistorn. Sealing is usually by a cup washer fitted against
a flat end face.

Type B-Double-acting hydraulic
actuators

Pistons of aluiminium, cast iron or steel, may be fitted with
lip seals ('U' packings) for operating pressures up to
21 MN/rn2 (3000 p.s.i.), or PTFE or metallic rings.

Hydraulic piston with "U packings

Hydraulic piston with PTFE sealing rings and bearer
bands

Scarf-step seahg ring arrangement, hydraulic or
pneumatic: (a) unidirectional; (b) double-acting

Figure 16.1 Various types of hydraulic pistons
B16.1