Application of the Month
From Heaven to Earth
October, 2007 - View all Application Examples
When you think of communications equipment you usually think of wires, cables, and electronic boxes. But there is a mechanical element when transmitting data between the ground and the sky.
A customer recently came to us with a variety of mechanical requirements for a large radar dish he was designing. While there was nothing unusual or spectacular about the design, it was an opportunity to provide several of the wide variety of drive components we offer, and work with the customer to help select the proper parts for his design.
The first component to be considered was the main drive for rotating the dish. It was to be servo controlled to provide precise positioning. Because of the low duty cycle and additional ratios down the line, we were able to suggest our Planetdrive series of economical servo gearheads. The 12 arc minutes of backlash was deemed adequate to meet the positioning parameters. Again, because of the low duty cycle, we were able to use the peak load capacity of the gearhead, which allowed downsizing, for a significant cost savings.
The second component to be considered was the bull gear drive box. The dish assembly was to be mounted on a large bull gear, which was to be driven by a smaller pinion. This provided a high reduction ratio and additional mechanical advantage. A right angle drive box was required because of the driveline configuration. We suggested our low back Tandler spiral bevel gearbox product line. These provide both high strength and extremely precise motion for smooth rotation. The pinion drive gear was to be mounted directly on the output shaft. Radial load calculations were preformed to be sure the pinion/bull gear separation forces did not exceed the bearing capacities.
The third component to be considered was an overload safety device to protect the drive system from an unexpected jam. Instead of using a standard shaft coupling to connect the jack shaft and input shaft of the spiral bevel gearbox, we selected an R+W integral coupling and torque limiter. These torque limiters come with a wide range of field adjustable torque settings and can be provided with four different re-engagement designs. In this case we selected the single position re-engagement design so the predetermined programmable servo controls could quickly return to home base. They also include a disengagement detection ring that can be read by a proximity sensor, which can alert a monitoring device to the overload.
The fourth component to be considered was a drive mechanism assembly to adjust the angle of the dish. For this we offered our Zimm screw jack product line. The basic design included a pivot bearing block mounted to the jack body to accommodate the varying angles. At the end of the screw we provided a clevis attachment for connecting to a bracket at the radius of the dish. To drive the jack we flanged mounted a small Watt drive inline helical gear motor. Protection elements include a protection tube below the jack body, a protective boot above the jack body, and anti-rotation on the screw to eliminate any side forces on the screw-connecting bracket. A rotary encoder was attached to the gear motor to determine position.
The result of all this work was the ability of the customer to purchase all of the drive and safety components from a single supplier along with the engineering and service support to make the proper selections. This saved a tremendous amount of time and assured that all components would work in harmony.
DieQua partners with a lot of our customers specifying multiple drive components within a single system. This provides high value for our customers, and our consultative approach assures that the correct components, to maximize the performance of the machine, are selected.
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