Planetary + Piggyback

An efficient retrofit solution offered by Italian manufacturer Ocmer Impianti and now available in North America via Scale-Tron’s ConcreteMixers.Biz combines

An efficient retrofit solution Û offered by Italian manufacturer Ocmer Impianti and now available in North America via Scale-Tron’s ConcreteMixers.Biz Û combines a high-performance planetary mixer with scales supplied as a prefabricated piggyback assembly. Since the piggyback scales come as a complete set, suitable for mounting on top of the mixer, nearly any batch plant can be upgraded in a few days. Piggyback scales offered in standard designs that match each mixer in capacity and charging speed ensure a smoothly functioning system, the supplier affirms.

Evidence of their effectiveness can be found in Ocmer’s own plants, which employ the piggyback scale systems for both its planetary and twin-shaft mixer models. Reportedly known throughout Europe for their longevity and reliability, the plants demonstrate the efficacy of the piggyback system, whether in retrofit or new applications. Features distinguishing Ocmer equipment are stainless steel hermetically sealed load cells, fully galvanized frame and hoppers, plus top-quality butterfly valves and actuators.

Though not widely offered by North American equipment manufacturers, scales for admixtures are making inroads from European suppliers. Dispensing admixtures by weight instead of volumetric metering improves accuracy and reliability, the company notes, especially by minimizing metering problems that arise with high-viscosity liquids and winter temperatures. To that end, the piggyback system offers multiple optional containers to be mounted as needed. A typical configuration may include a central cement scale, bracketed by a water scale and a second powder scale that can be used for fly-ash, white cement or silica fume. Also easily attached to the mixer is an add-on skip-hoist, featuring a double-rope design with full safety cut-offs.

Ocmer’s planetary mixers are equipped with a one-piece reduction and planetary gearbox containing large oil-bath lubricated gears for high strength and reliability to ensure fast, compulsory mixing action, the manufacturer asserts. Thorough mixing in both vertical and horizontal directions is achieved by the combination of a wider mixer body for minimal material depth and high-back, scooped paddles.

Discharge is fast and complete, even with high-slump mixes and SCC, where lower-profile paddles tend to skate underneath the mix. Paddles are made of certified 600 Brinell ni-hard cast iron for extended wear, and a floor of 18-mm Hardox provides long service life without risk of broken pieces and jammed paddles as cast tiles wear thin. Arms and stars are fabricated, rather than cast, to maximize strength and reduce the chance of breakage. Performance is further enhanced by discharge doors with hydraulic action for complete sealing, automatic lubrication of main gearbox and other bearings, optional dust-collection air bag, and high-pressure washout.

Thus, a mixer equipped with the piggyback scale and add-on skip hoist can provide a highly effective central mix plant, requiring only a set of low-profile aggregate bins and conveyor scale to feed the skip hoist. Accessory components can be built locally or obtained through dealers and OEMs throughout the U.S., Canada and South America.

Information provided by, a mixer and plant-equipment specialty division of control-systems supplier Scale-Tron Inc.