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Adjustable Drives
 Zero-Max is a mechanical adjustable speed drive. Five sizes provide constant torque of 12 to 200 inch pounds throughout the speed range. The speed range is infinitely adjustable from 0 to 1/4 of the input speed under full rated load. This is generally stated as 0-400 RPM under full rated load assuming an input of 1800 RPM. For lower speed/higher torque applications, some Zero-Max Drives are available with or right angle gear heads. Some Zero-Max Drives may be purchased with standard electric motors or they may be connected to any rotating power source up to 2000 RPM. Speed adjustments are easily made by moving a lever control through an arc or turning the hand-wheel of a screw type control. In either case, easy and precise speed control settings are possible. Zero-Max Drives may be used as a primary or secondary drive. Zero-Max Drives are available in five sizes providing constant torque of 12 to 200 inch pounds throughout the speed range. Zero-Max Drives are also available with optional gear heads, motors and C-flange adapters. Zero-Max Adjustable Speed Drives are manufactured and assembled in our Plymouth, Minnesota, USA facility. All components are thoroughly inspected prior to assembly. After assembly, each unit is tested and run for at least four hours to assure consistent quality from unit to unit. Over 1 million Zero-Max Drives have been put to work in a wide variety of applications. They are available from distributors in all major markets throughout the world. For more information on variable speed drives, contact us or click here to find your local sales representative. Externally, the Zero-Max Drive consists of a rugged, sealed cast case, an input shaft, output shaft and speed control. Speed of the output shaft is regulated precisely and easily through a control lever which includes a convenient locking mechanism or a screw control to hold speed at a desired setting. Models are available with output in clockwise or counter-clockwise rotation to meet individual speed control requirements. Two models are equipped with a reversing lever that permits clockwise, neutral and counter-clockwise operation. The general principle of operation of Zero-Max Drives gives infinitely adjustable speed by changing the distance that four or more one-way clutches rotate the output shaft when they move back and forth successively. The number of strokes per clutch per minute is determined by the input speed. Since one rotation of the input shaft causes each clutch to move back and forth once, it is readily apparent that the input speed will determine the number of strokes or urgings the clutches give the output shaft per minute. For example, with four clutches working in series and an input of 1800 RPM, the output shaft is urged 7200 times per minute (1800 x 4) or 120 times per second (7200 ÷ 60). If the input speed is dropped to 900 RPM, the shaft is urged only 3600 times per minute and the maximum output speed will be cut in half.
Looking at Figure 1, the input section, consisting of a shaft (A), eccentrics (B), and connecting rods (C), converts rotary motion into linear motion. At the zero setting, the main links (D) pivot on points (H) and (J) without moving the clutches. At any setting other than zero, the clutches (E) transfer the linear motion back into rotary motion and drive the output shaft (F). A control link (G) swings through arc (K) when the control lever is moved. At any point along arc (K) a different output speed is produced because the direction of throw of the connecting rod is altered from vertical (Figure 1 zero RPM position) toward horizontal (Figure 2 maximum speed position), varying the length of the strokes the main links deliver to the overrunning clutches. Features
Benefits
To achieve the exact performance characteristics you desire, Zero-Max provides the following matching components: For Model E and JK Drives, a selection of gearheads and motors is available. For models Y, QX and ZX Drives, C-Flange adapters are available for connecting customer supplied motors to the drive you have selected. Lever control is standard on all drives. Optional controls include: screw control, extended screw control, extended lever control, extended control shaft, plus flatted and drilled control levers. Direction of output rotation must be specified and is independent of input direction. Model numbers ending in "1" are CCW output, "2" are CW output and "3" are reversible. Zero-Max variable speed drives are used on a wide variety of machinery. They may be used as a primary or secondary drive and are available with several control options and shaft arrangements. Applications include: textile machinery such as looms; food processing machinery such as hamburger presses; agricultural machinery including grain dryers and seeder drives; printing presses utilizing high speed sheeters for stacking finished sheets; metalworking machinery; packaging systems, automated sewing systems, conveying and specialized machines.
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