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Step 4: A Model 501 torque arm bracket is required to prevent rotation of the driver pulley handwheel and allow speed adjustment while the motor is running. If a remote control or linear actuated drive is preferred, the same basic package can be used, but the driver pulley will be a Model HEC-30 for electric remote control (also order the CH-2601 control station) or a Model HEC-30 for electric remote control (also order the CH-2601 control station) or a Model HLA-30 for linear actuation. For details on these pulleys, refer to pages VSD-59 and VSD-60. The 501 torque arm bracket is not necessary when using the HLA pulley. After assembling the complete drive package, you will end up with four components: an HM-30 x 3/8 inch manual driver speed pulley; a 34407 x 5/8 inch spring loaded driven pulley; a 4430V600 belt; and a 501 torque arm bracket.

Variable Speed Drives - 7199 Variable Speed Drives Fixed Center Example

Selection Process

Step 5: A suitable motor base must be selected based on the NEMA motor frame size. For a 56 frame motor, there are several choices: the Model 48/56 economy base, the Model 200 tilting base, the SMB-143 steel sliding base, or on of the two cast iron bases, 145-60 and 135.After assembling the complete drive package, you will end up with four components: a 160 x 5/8 inches variable speed pulley; a 6 inch pd companion sheave for an “A” belt with a bore to fit the driven shaft (not supplied by Lovejoy); an A33 drive belt (not supplied by Lovejoy); and a 48/56, 200, SMB-143, 145-60, or 135 motor base. Step 4: The belt selection chart shows 7.9 inches as the minimum distance for a 160 pulley and a 6 inch sheave. Moving across to the left in that chart, the belt for that center distance is an A33. You can see that the Model 160 pulley requires 2.7 inch travel to achieve full speed range, so the maximum center distance will be 7.9 (minimum cd) + 2.7, or 10.6 inches. Step 3: To select a drive belt, refer to the Belt Selection chart for the HM-30 drive. The 4430V600 belt is chosen because it is closest to the 16-1/2 inch center distance requirement. As the Belt Selection chart shows, the actual center distance is 16.53 inches. Important Note: When the driven speed range is critical, it is necessary to set up the drive at the exact center distance specified for the belt selected. Any variation from the correct center distance will result in a driven speed range that is different from that shown in the drive selection charts. Step 2: The HM-30 driver is selected, and based on the motor HP, speed, and “C” mounting configuration, the Model 34407 driven pulley is most suitable. This drive is rated at 10 HP from 1,750 to 3,300 RPM driven speed, which is nearest to our 8 HP driven requirement. The Driven Speed chart shows that, with a 1,750 RPM motor, this drive will provide a range of 640 to 3,200 RPM at the pump. A check of stock bore sizes shows that the HM-30 is available in 1-3/8 inches (the motor shaft size), and the 34407 driven pulley is available with a 1-5/8 inch stock bore Step 1: The Hexadrive is selected because of the horsepower requirement. Fixed center drives are rated as constant HP drives from base (motor) speed to maximum driven speed. According to the ratings for 1,750 RPM motors, the drive package most suitable for this 8 HP requirement is a 10 HP drive. Refer to the drive selection data on page VSD-58 for a 10 HP drive.

Selection Examples: Fixed Center Drives

Hexadrive Series Selection Example

A fixed center variable speed drive is needed for a centrifugal pump that has an 8 HP peak at 2,000 RPM. The motor is rated for 10 HP @ 1,750 RPM, with a 1-3/8 shaft. The pump shaft is 1-5/8 inches. Shaft center- to-center distance is approximately 16-1/2 inches. There is no room to accommodate an adjustable base or to move the motor back and forth for speed adjustment, so a fixed center drive is preferred. Motor shaft and driven shaft both are oriented in the same direction, so this is a “C” drive configuration. The service factor for a centrifugal pump is 1.0 (see page VSD-68).
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