McLanahan Corporation’s MD Vibratory Screens Troubleshooting Guide focuses on situations such as what to do if the motor is too hot, if the motor is drawing excessive current, if the machine is making a loud rattling noise, and more.
MD Vibratory Screens Support
MD Vibratory Screen Maintenance
How do I change a screen?
MD Vibratory Screens are designed so that the screens can be changed quickly and easily. The proper procedure for changing a screen is as follows:
- Stop the feed.
- Turn off the vibrating motor and lock out power to the machine.
- Remove the rear cover by tapping the holding wedges until they come loose.
- Loosen the nuts on the screen tensioner until the lap on the rear edge of the screen deck is free. A special socket is provided to facilitate this process.
- Allow the screen deck to slide forward until the lap on the front edge of the screen deck is free. If the front edge sticks, it can be freed one of two ways: The front edge can be reached through an inspection port on the side of the unit and pulled free, or the special screen installation tool that was provided with machine can be inserted under the screen deck to push the front screen lap off the front hook.
- Slide the screen out through the rear of the machine.
- Insert the new screen from the rear of the machine and hook the front screen lap over the front cross-member hook. If necessary, the front edge can be guided using either of the two methods discussed previously in Step 5.
- Hook the screen tensioner under the screen lap at the rear edge of the screen deck, and tighten the nuts against the spring capsules, thus tightening the screen cloth.
How often should I inspect the bolts?
All bolts and wedges should be checked periodically to ensure that they remain tight. The most critical bolts are the motor mounting bolts and the motor base bolts. These bolts are Grade 5 and should be tightened in accordance with the manufacturer's recommendations. Refer to the Installation, Operation and Maintenance Manual for more information.
Special attention should also be given to the bolts on the front chute/cover and the discharge chutes, since these items are designed to be as light as possible. The frequency of these checks is dependent on the amount of time that the screen is in service.
How do I tension the screen?
MD Vibratory Screens are fitted with special disc spring capsules to provide the proper tension on each screen. These capsules fit over threaded rods that extend from the screen tensioners, which grip the rear edge of each screen. The capsules are positioned so that the moveable piston points toward the screen. There is a flat washer on the piston end of the capsule and a tightening nut on the opposite end. Proper tension is obtained by tightening the nut on the threaded rod until the piston of the capsule is completely contracted.
Note: The capsules are designed to just come in contact with the flat washer when the piston is completely contracted. Do not over tighten. Continue to tighten the nut will cause damage to the screen cloth or to the screen frame.
What will happen if the liners wear through?
If the liners are permitted to wear through, the MD Vibratory screen frame will be subject to wear.
Operational Best Practices
How should I feed the MD Vibratory Screen?
The efficiency and effectiveness of the Model SM screen depends greatly on how the material is fed into the machine. In order to achieve quality separation at high capacities, the md screen should be fed with an even and slow-moving flow of material. A variety of feeding devices may be used, including vibrating feeders and dirt boxes. General rules for feeding an MD Vibratory Screen are as follows:
- The speed of the material fed onto the feed plate should be the minimum required to obtain the desired volume. A slow-moving deep layer of material is preferred over a fast-moving shallow layer.
- The material must be fed uniformly across the full width of the machine.
- The direction of feed material flow should be from the rear of the machine and parallel to the sides.
- The feed should be such that a column of material cannot build on the feed plate. Such a condition may cause choke loading.
- The feed material should not drop more than 24 inches onto the feed plate.
What should I do during startup?
• Make sure that all the suspension springs are properly located, and securely mounted.
• Make sure the sides of the machine are vertical.
• Make sure the machine is free to vibrate without any obstructions, and without touching any surrounding structure or equipment.
• Make sure that the proper screens are fitted on the MD screen, and that all of the them are properly tensioned.
• Make sure that ALL covers and chutes are securely fastened.
• Make sure that the electrical supply is correct for the motors supplied.
• Make sure that all the connections in the vibrator terminal boxes are correct, and that all the connections are secure.
• Make sure that the out-of balance weight settings are exactly the same for both sets of weights, and that both sets of weights are aligned perfectly.
• Make sure that all the electrical cables are properly supported and are notsubject to wear once the machine is put into operation.
I hear a rattling noise in my machine. Is this normal?
Under normal operating conditions, the machine should be quiet, with only a slight humming sound present. If any rattling occurs, it is normally an indication that something is loose or broken. An exception to this is that MD screens equipped with pneumatic tensioning are prone to rattle for 10-20 seconds, until the air cylinders pressurize and tighten the screens. If an unusual noise is detected, shut down the machine immediately and turn the power off. With the machine de-energized, located the source of the noise and correct the problem.