Power Jacks Rolaram Linear Actuators - Manual (Page 23)

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LINEAR ACTUATORS
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Rolaram
Actuator
Spring return actuator, ball screw version, in-line drive.
Application
Failsafe operation of ventilation dampers.
Linear Actuation Requirements
The actuator opens and closes the damper and maintains a 3 kN
load to ensure that the damper is sealed. The damper must open
and close in 2 seconds and operate at 250°C for 1 hour. In the
event of power failure, the actuator must failsafe in the closed
position.
Solution
One off ball screw actuator is fitted onto each damper. The actuator contains a pre-
loaded spring and is fitted with a high temperature brake motor. The internal spring
and drive configuration will allow the ram to retract automatically in the event of
power failure. Three adjustable limit switch positions are provided and the stroke can
be set within the allowable 120 mm, by adjusting these switches. All components are
selected for the appropriate approved temperature requirement. The actuator has a
fire test certificate for operation at 250°C for 1 hour.
Actuator
R175 model, roller screw version, right angle drive.
Application
Positioning a weir gate for water level adjustment.
Linear Actuation Requirements
The actuator moves a dynamic load of 150 kN (static load of 330 kN), at a linear speed
of 240 mm/minute, has a stroke of 2700 mm and a life requirement of 40 years.
Solution
One actuator is fitted on each weir gate and has several special
features:
•
Universal joint at the ram end to compensate for misalignment and to resist
the load torque
• Geared motor drive with hand wind facility
• Positional indication and end of travel limit switches
• Non contaminating grease
This application is in a remote location and an electro mechanical solution was
preferred over hydraulics due to low power requirements, no expensive hydraulic
power pack, no hydraulic fluid leakage i.e. no water contamination and minimal
maintenance.