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2013FallShotcreteEMag

Nozzleman Knowledge Fig. 1: Bowl-type rotary gunite machine Fig. 2: Worn plate (left), new plate (right) (dry-mix shotcrete machine) nient means of oiling and adjusting the felt seal from outside the hopper without dismantling the machine. This lubrication and adjustment is achieved through strategic access holes designed into the hopper. A felt seal that is in good working condition is critical to avoid letting dust escape between the hopper and the wear plate. As stated previously, excessive dust on the job can create a health risk to workers and must be controlled. The gooseneck contains a polyurethane liner to prevent wear directly on the steel surface of the gooseneck. Replace the liner when it has worn through to prolong life of the gooseneck. The Fig. 3: Gunite machine view of wear pad amount of wear is dependent on the type of mate- rials being used; however, liners should provide approximately 80 yd3 (61 m3) of service. It is not advisable to operate the gun without this goose- neck liner for economic reasons. The liner comes with a smaller price tag than the gooseneck, so it only makes sense to keep the usable liner in place to accommodate the wear. Various parts of the gunite machine require regular lubrication. Before every job, lubricate the Fig. 4: New wear pad (left), worn wear pad (right) bowl and plate with oil as specified in the equipment manual. When oiling the feed bowl, make sure to into the system is clean and the lubricator gives thoroughly coat the pockets of the bowl, which the passing air a small amount of oil. Both ensure primes the steel for use and helps reduce the amount smooth operation of the air motor. Inspect the air of dried material that sticks to the surface. The bowl filter weekly and clean if needed. New machines and plate touch each other directly in the machine, may arrive from the factory with an empty air so proper, regular lubrication helps reduce wear lubricator that is also closed to oil flow. It is between these two components (Fig. 5). critical when receiving delivery of a new machine Many gunite machines are entirely powered to fill this lubricator and adjust the flow of oil. by air, which is used independently to rotate the Before each job, make sure that the air lubricator feed system and to propel dry material out of the is filled with oil according to the directions in the gooseneck through the material hose to the nozzle. equipment manual. Manuals should include rec- These machines include an air motor that controls ommendations on the number of drops per second rotation of a series of gears and the main shaft. or minute, such as one drop every 10 to 15 sec- Air lines (that is, plumbing pipes and fittings) that onds. On many gunite machines, the air motor is deliver air to the motor are equipped with a filter connected to a gear box, which requires lubrica- and lubricator. The filter ensures that air going tion. You should be able to check the oil level in Shotcrete • Fall 2013 39


2013FallShotcreteEMag
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