Linear & Rotary Damper Drives
Committed to providing the most economical offering to each application problem consistent with an assured quality solution.
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Engineered Solutions to Your Tough Steam Problems
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MIDWEST CONTROLS CO.
Damper Drive Systems feature:
- Field Proven Components All components have been proven in field services applications and selected based on ruggedness, reliability and accuracy.
- Rugged Construction All components are mounted on heavy duty, welded steel framework.
- No External Covers All components are individually sealed and designed for exposed plant applications and require no external covers for protection.
- Modular Construction All components can be easily removed and replaced. Optional components can be added at anytime.
- Installation Flexibility Standard mounting dimensions are based on existing common drive systems, however, special mounting dimensions can be accommodated easily. The rotary output arm is adjustable through 360 degrees and cylinders can be selected to meet specific linear travels.
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| Linear Damper Drive Units |
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| Rotary Damper Drive Units |
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Design Considerations
- Enclosure
- Operating Cylinder
- Drive Shaft
- Drive Shaft Bearings
- Output Arm Connection
- Manual Override
- Postitioner Calibration
- Installation
- Maintenance
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ENCLOSURE
Most competitive units rely on enclosure covers and panels to protect the drive cylinder, couplings and bearings from the normal harsh, power plant environment. As often happens after calibration or routine maintenance, the covers and panels are not secured due to oversight, poor fit or rust and corrosion resulting in premature failure of cylinder seals, shaft bushing and drive couplings.
Midwest designed with all independently sealed components inherently designed for application in dirty plant locations without the need for auxiliary external covers.
OPERATING CYLINDER
Most competitive units rely on a linear, double acting piston cylinder with a piston rod seal that is subject to excessive wear from airborne particles and deterioration of output torque as air leakage increases.
Midwest designed using existing, field proven quarter-turn valve actuators which have the piston rod sealed from all environmental elements. Double acting and spring return designs are available.
DRIVE SHAFT
Most competitive units rely on conversation of linear cylinder motion into rotary motion through a rod end bearing pinned to a clevis attached to the drive shaft. This rod end bearing and pinned connection are subject to excessive wear from foreign particles along with the normal modulating operation wear which results in hysteresis and deadband.
Midwest designed with actuators featuring sealed scotch yoke or rack and pinion type linear to rotary conversion and a straight-thru drive shaft from the actuator output shaft to the output arm. This design along with close tolerance couplings virtually eliminates the existence of hysteresis and deadband in the drive shaft.
DRIVE SHAFT BEARINGS
Most competitive units are designed with high friction bushings supporting the output shaft. By virtue of the inherent design side loads introduced by the cylinder rod pushing on the rotary shaft clevis, the bearing loads are quite high and results in loss of output torque which gets progressively greater as the bushings wear.
Midwest designed with a sealed ball bearing supporting the shaft with high load bearing characteristics for highest efficiency, minimal loss of output torque and low maintenance.
OUTPUT ARM CONNECTION
Most competitive units rely on a splined shaft connection to provide arm rotation adjustment. The splined shaft is subject to wear and resulting added hysteresis and deadband. Often the solution is to weld the arm to the shaft which necessitates replacing both the shaft and output arm due to bushing wear.
Midwest designed the output arm connection to the shaft with a unique "zero deadband" truncated wedge-tooth connection for arm rotation adjustment.
MANUAL OVERRIDE
Most competitive units rely on a manual "lever" override with high manual force required or manual declutch mechanisms that are subject to jamming and either bending or breaking the split nut trunnion which makes the manual override inoperable.
Midwest makes available a separate declutchable manual worm gear operator which is independent of the pneumatic operator. This provides for low manual rim pull forces and allows for mechanical lock in position or manual operation in the event the positioner or piston operator is removed for maintenance purposes.
POSITION CALIBRATION
Most competitive units locate the positioner in a position close to the base of the unit which requires an instrument technician to assume a very uncomfortable body position or lay prone on the floor to perform positioner calibration. In addition the position feedback is through linkage which is subject to wear and deteriorating performance.
Midwest designed for the positioner to be direct coupled to the outboard side of the actuator which eliminates feedback linkages and puts the positioner in a location which is very accessible for calibration.
INSTALLATION
All competitive units have different mount dimensions and different output arm dimensions which results in added installation costs to install a replacement unit of a different manufacturer.
Midwest designed with a heavy duty steel framework that can be manufactured with mount dimensions and output arm dimensions matching most competitive units. This eliminates added installation costs when replacing an existing unit.
MAINTENANCE
Most competitive units require removal of protective covers and panels and that detailed disassembly and maintenance to be performed at the location of installation.
Midwest designed around a modular concept that allows for simple removal of the positioner or actuator with subsequent maintenance in the instruments shop with handy access to all necessary tools and calibration/test instrumentation.
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Quality Integrity Service Consultation Support
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