Nexen VC500 837450 - Manual (Page 9)

9 FORM NO. L-21156-F-0209
OPeraTIOnal mODeS
Figure 7
nOrmal SPrInG enGaGeD mODe
This mode is for occasional duty, non-cyclic applications only. A hold-off pressure of 4.1-4.8 bar [60-70 psi] is used
to compress the spring inside the Actuator canister. A control signal is used to release the hold-off pressure, thus
applying full spring-engaged torque to the brake (See Figure 7).
SPrInG enGaGeD-Dual aIr mODe
This mode allows the selection of any value of spring engaged torque (from zero to full scale) available with a particular
disc size by relieving a percentage of the minimum Hold-Off pressure 4.1 bar [60 psi]. The remaining pressure,
balanced against the spring force, reduces the output of the Actuator (See Figure 8).
examPle: A standard spring set brake with a 18 inch disc has a full rated spring engaged torque of 3,480 Nm
[30,800 in-lb] when using the minimum hold-off pressure of 4.1 bar [60 psi]. If it is desired to have 60% of this torque
or 2,016 Nm [18,000 in-lb], relieve the hold-off pressure 60 percent or 1.9 bar [36 psi], leaving 2.2 bar [24 psi] hold-
off pressure.
Figure 8
nOrmal ServICe mODe
Below is a standard air brake control circuit. On-off air control is achieved by the 3-way valve. Torque is accomplished
by the regulation of air pressure.
nOTe: maximum operating pressure is 8.3 bar [120 psi] (See Figure 6).
3-Way Control N.C.
Filter
Lubricator
3-Way Manual
Control
Air Supply
Regulator
Power
Source
3-Way Manual
Control
Air Supply
Regulator
Power Source
3-Way Control N.C.
Power Source
Regulator
3-Way Control
N.C.
Lubricator
Filter