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7. BRAKE ACCUMULATOR
1)
STRUCTURE
2
2
)
OPERATION
(1)
Purpose
Fluids are practically incompressible and are thus incapable of accumulating pressure energy. In
hydropneumatic accumulators, the compressibility of a gas is utilized to accumulate fluid. The
compressible medium used in the accumulators is nitrogen.
In braking systems, the purpose of the accumulators is to store the energy supplied by the
hydraulic pump. They are also used as an energy reserve when the pump is not working, as a
compensator for any losses through leakage, and as oscillation dampers.
(2)
Operation
The accumulator consists of a fluid portion (A) and a gas portion (B) with a diaphragm (C) as a
gas-tight dividing element. The fluid portion (A) is connected to the hydraulic circuit, causing the
diaphragm accumulator to be filled and the gas volume to be compressed as the pressure rises.
When the pressure falls, the compressed gas volume will expand, thus displacing the
accumulated pressure fluid into the circuit.
The diaphragm bottom contains a valve disk (D) which, if the diaphragm accumulator is
completely empty, closes the hydraulic outlet, thus preventing damage to the diaphragm.
(3)
Installation requirements
The accumulators can be fitted in the hydraulic circuit, directly on a component or in blocks on
suitable consoles.
They should be fitted in as cool a location as possible.
Installation can be in any position.
B
A
C
D
(770-3ATM) 4-22
4-25
Item
Diameter
Mounting height
Nominal volume
Priming pressure
Operating medium
Operating pressure
Thread
Priming gas
A Fluid portion
B Gas portion
81L1-0004
110mm
164mm
0.7
50kgf/cm
2
Oil
Max 150kgf/cm
2
M18 1.5
Nitrogen
C Diaphragm
D Valve disk
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