When field installing or replacing sheaves, install sheaves on fan shaft and motor shaft for minimum overhang. (See Fig. 13.) Use care when mounting sheave on fan shaft; too much force may damage bearing. Remove rust-preventative coating or oil from shaft. Make sure shaft is clean and free of burrs. Add grease or lubricant to bore of sheave before installing.

The 39L fan, shaft, and drive pulley are balanced as a com- plete assembly to a high degree of accuracy. If excessive unit vibration is present after fan pulley replacement, the unit must be rebalanced. For drive ratio changes, always reselect the mo- tor pulley — do not change the fan pulley.

ALIGNMENT — Make sure that fan shafts and motor shafts are parallel and level. The most common causes of mis- alignment are nonparallel shafts and improperly located sheaves. Where shafts are not parallel, belts on one side are drawn tighter and pull more than their share of the load. As a result, these belts wear out faster, requiring the entire set to be replaced before it has given maximum service. If misalignment is in the sheave, belts will enter and leave the grooves at an angle, causing excessive belt cover and sheave wear.

1.Shaft alignment can be checked by measuring the distance between the shafts at 3 or more locations. If the distances are equal, then the shafts will be parallel.

2.Sheave alignment:

Fixed sheaves — To check the location of the fixed sheaves on the shafts, a straightedge or a piece of string can be used. If the sheaves are properly lined up the string will touch them at the points indicated by the arrows in Fig. 14.

Adjustable sheave — To check the location of adjustable sheave on shaft, make sure that the centerlines of both sheaves are in line and parallel with the bearing support channel. See Fig. 14. Adjustable pitch drives are installed on the motor shaft.

With adjustable sheave, do not exceed maximum fan rpm.

3.Rotating each sheave a half revolution will determine whether the sheave is wobbly or the drive shaft is bent. Correct any misalignment.

4.With sheaves aligned, tighten cap screws evenly and progressively.

NOTE: There should be a 1/8-in. to 1/4-in. gap between the mating part hub and the bushing flange. If gap is closed, the bushing is probably the wrong size.

5.With taper-lock bushed hubs, be sure the bushing bolts are tightened evenly to prevent side-to-side pulley wob- ble. Check by rotating sheaves and rechecking sheave alignment. When substituting field-supplied sheaves for factory-supplied sheaves, consider that the fan shaft sheave has been factory balanced with fan and shaft as an assembly. For this reason, substitution of motor sheave is prefer-able for final speed adjustment.

Install V-Belts — When installing or replacing belts, al- ways use a complete set of new belts. Mixing old and new belts will result in the premature wear or breakage of the newer belts.

1.Always adjust the motor position so that V-belts can be installed without stretching over grooves. Forcing belts can result in uneven stretching and a mismatched set of belts.

2.Do not allow belt to bottom out in sheave.

3.Tighten belts by turning motor-adjusting jackscrews. Turn each jackscrew an equal number of turns.

4.Equalize belt slack so that it is on the same side of belt for all belts. Failure to do so may result in uneven belt stretching.

5.Tension new drives at the maximum deflection force recommended (Fig. 15).

Fig. 13 — Determining Sheave-Shaft Overhang

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Carrier 39LE, 39LB, 39LD, 39LA, 39LC, 39LF, 39LH03-25, 39LG specifications Determining Sheave-Shaft Overhang
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39LG, 39LH03-25, 39LD, 39LE, 39LB specifications

The Carrier 39 series, encompassing models 39LA, 39LF, 39LC, 39LB, and 39LE, represents a prominent line of rooftop packaged units that combine robust performance, energy efficiency, and advanced technology for commercial applications. Designed to provide reliable heating and cooling solutions, these units stand out for their versatility and innovative features.

The 39LA model offers high efficiency and flexibility, making it ideal for various building types. It incorporates advanced economizer capabilities that enhance indoor air quality while reducing energy costs. The unit is equipped with a dual-walled cabinet, which not only improves durability but also ensures quiet operation, making it suitable for noise-sensitive environments.

The 39LF model further enhances energy savings, featuring a unique hybrid heat pump system. This system allows for both heating and cooling through an integrated design, reducing the need for separate systems and streamlining maintenance requirements. The 39LF also boasts high Seasonal Energy Efficiency Ratio (SEER) ratings, contributing to lower operating costs without compromising comfort.

The 39LC variant excels in humid climates, employing advanced dehumidification technologies that effectively manage indoor moisture levels. This model is often utilized in environments such as gyms, restaurants, and hotels where humidity control is vital. Its variable-speed compressors adjust output based on demand, optimizing energy consumption while maintaining consistent comfort levels.

The 39LB model focuses on enhanced filtration and air quality improvements. Its engineered design accommodates high-efficiency particulate air (HEPA) filters, crucial for spaces that require stringent air quality standards. This model also includes smart controls that allow for precise temperature adjustments, ensuring optimal comfort in any setting.

Finally, the 39LE unit emphasizes user-friendly interfaces and smart technology integration. The built-in Wi-Fi capability enables remote monitoring and operation, allowing managers to adjust settings from anywhere, improving overall energy management. Additionally, the 39LE’s compatibility with Building Management Systems (BMS) facilitates seamless integration into existing setups.

In summary, the Carrier 39 series 39LA, 39LF, 39LC, 39LB, and 39LE present a comprehensive array of features designed for various commercial heating and cooling applications. With an emphasis on energy efficiency, advanced air quality management, and user-friendly technology, these units continue to set the standard for rooftop packaged units in the industry. Their innovative characteristics not only enhance comfort but also promote sustainability, making them a smart choice for modern commercial environments.
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