Selecting equipment to grind, hone and polish can be a daunting task. There are several factors to take into consideration, among them the equipment's power requirements, weight, motor size, overall dimensional size, working dimensions and direction or directions the abrasives rotate. At this point you may be thinking, "What is so daunting? It looks pretty basic to me." There is a saying in this business, "The more you learn the more you realize how little you know."
As you read this article keep in mind it addresses common or typical machines; specific characteristics vary from one manufacturer to another. Let's examine the selection factors.
Power requirements. Equipment is either powered by cord electric, battery electric or propane, and in some cases hydraulic driven motors are used. With propane power there are no cords and no electrical requirements other than the battery used for starting the machine. Electrical requirements for cord electric equipment are typically 110 volt single-phase, 220 volt single-phase or three-phase, and 460 volt three-phase. Some 220 volt pieces of equipment allow you to run them single- or three-phase. Amperage requirements can range as low as 20 amps and as high as 60 amps.
Keep in mind high motor voltage equals lower amperage requirements and smaller gauge power cord. Although, many electrical panels are thought of as 220 volt and often their true output is only 208 volts. If you plug your machine into a source that is only 208 volts make sure the equipment has the ability to run on the lower voltage. If not you will have to invest in a transformer, often referred to as a buck booster, to boost the voltage. NOTE: Always use a qualified, licensed electrician when hooking up your equipment for use.
Weight. Walk-behind equipment ranges in weight from 110 pounds to over 2,000 pounds before optional weights are applied. Ride-on equipment can weigh over 13,000 pounds. Equipment weight is important from a transportation point of view, but more important is the actual weight or head pressure over the abrasives.
Motor size. Motors range from 1 hp on a small, single-head rotary machine to 40 hp on a walk-behind machine with a multi-rotary head. There are three variables that affect the amount of power required for a machine to efficiently operate - how much contact area there is between the abrasives and the concrete surface, the grit designation being used, and the weight of the machine. These variables contribute to friction between the abrasive and concrete. The higher the friction, the more power required to drive the abrasives.
Overall dimensional size. You can find equipment small enough to fit in the back of a small hatchback and equipment so large it will only fit on a flat bed tractor trailer. Equipment comes in all shapes and sizes. Some break down into multiple pieces for easier transportation and some are all one piece.
Working dimensions. This is defined as the overall area the abrasives affect when the machine is running. Equipment working dimensions can range from square and 14 inches to round and 15 inches to 98 inches with multiple planetary heads.
Push, propel or ride on. Some machines are designed to be pushed, pulled or moved side to side while others are propelled with motor-driven wheels or come as ride-on units.
Belt/chain, gear or direct drive. The rotating heads of the machine are most often driven by a main or centralized motor that uses a belt or chain in conjunction with a pulley system. Some equipment eliminates all belts or chains and uses a gear system. Small, single rotating head machines are usually driven directly from the motor.
Abrasives drive. There are machines that have a large fixed single rotating head that may measure 15 to 20 inches, fixed dual rotating heads that are positioned side by side, machines that have two to eight rotating heads that intertwine in a gear-like fashion whose working width is up to 56 inches, and then there is planetary equipment where one large head rotates in a direction in addition to smaller satellite heads that also rotate in the opposite or same direction.