Adjustable Motor Mounting Bases

There are many components used in belt power transmission systems that are critical, but some may not be as readily apparent as others. An example is electric motor mounting bases.

While motors can be bolted directly to structures by their mounting feet, this does not always allow for necessary movement and adjustability. Adjustable motor bases are commonly used to secure motors while providing a means of positional adjustment. While types, designs, and methods of adjustment vary with brands and size, the best designs adjust with large linear screws.

Focusing on belt drive systems, adjustable motor bases are used to shift motor positions for belt removal and for new belt installation. They are also used to shift motor positions for belt pre-tensioning. Another critical function of adjustable motor bases is adjusting and maintaining motor shaft position for alignment with driven shafts. Accurate shaft alignment is very important for good belt performance, especially with synchronous belt drive systems.

Figure 1 – Single Screw Adjustable Motor Base

Figure 1 illustrates an adjustable motor base utilizing a single adjustment screw. While screw adjustment is superior to bases that only slide, side forces exerted by belt drives on motor shafts generate torsional forces. Single screw adjustment bases often deflect resulting in non-parallelism between motors and driven components. Correction with single screw designs can only be accomplished by applying external forces to motors and bases, which becomes difficult with increasing motor size. Single screw adjusting bases are used mainly for their economics, but do not generally maintain adequate shaft alignment nor belt tension.

Figure 2 – Duel Screw Adjustable Motor Base

Figure 2 illustrates an adjustable motor base utilizing duel adjustment screws. While motor bases of this type generally have fairly heavy duty designs, small torsional deflections can be compensated for fairly easily while applying pre-tension to belts. Adjustments to shaft alignment and belt tension levels are easy and accurate with this type of motor base design.

The design and condition of adjustable motor bases can have a critical effect on belt drive service and performance. When performing maintenance operations, replacing belts or converting V-belt drives to synchronous drives, consider upgrading inferior and insufficient motor bases to heavy duty duel adjusting screw types.

Underwriters Laboratories (UL) Certification for Industrial Belts

When UL certification is desired for a product that includes a belt drive, it is typically applied for by an original equipment manufacturer for their finished product (e.g. air conditioner, compressor, lawn mower, vacuum cleaner etc.) rather than at the component level (e.g. v-belt, synchronous belt, bushing, pulley, etc.).  Gates has not applied for UL approval of  v-belt or synchronous belt drive components.

Synchronous Belt Drives with a BANG!

During the startup of your synchronous drive you may occasionally hear a loud “Bang!” coming from the drive system.  This could be the result of belt tooth jumping, or belt ratcheting which is more prevalent in drives that are under-tensioned or have mismatched tooth forms. Though the installation tension may be correct and sufficient, ratcheting could still occur because of a loss in structural rigidity.  This is due to the fact that belt installation tension calculations do not take into consideration the possible differences in structural rigidity.  Therefore belts which appear correctly tensioned when idle may become under-tensioned when operating, or more specifically during the startup period. 

This belt ratcheting issue is more prominently in direct, across the lines starts in which severe shock loads are introduced to the system during this period.  This severe shock load results in frame deflection which, if the structural rigidity of the drive is inadequate, causes loss in belt tension and potential tooth ratcheting.

One method to determine if the structural rigidity of the system is of a concern is to simply stretch a taught piece of string between the DriveR and DriveN supports in such a manner that any significant movement will result in the string to sag or break.  This of course should be performed with the drive disabled and the proper lock out, tag out procedure followed.  Once the string is set, simply press both the tight and slack side of the belt together and monitor the strings movements.  If significant sag occurs then the structure rigidity should be increased or the belt installation tension will need to be increased above the recommended value.  This increase is used to account for the high startup loading and resist tooth ratcheting given this ratcheting can severely damage the belt and result in decreased belt life and performance. For any additional questions feel free to contact us at ptpasupport@gates.com or 303-744-5800.

2013 FIRST Scholarship

In support of the FIRST^® mission, Gates Corporation is offering six merit-based scholarships, each for $2,000, to select participants in the 2013 FIRST Robotics Competition. This scholarship may be used for any undergraduate science-based course of study at any United States college or university that holds accredited status. More information can be found online at www.gates.com/FIRST.

Eligibility

To be eligible for this scholarship, you must:

·         Be a senior in high school for the 2012-2013 school year

·         Have participated on a team during the 2013 FIRST Robotics Competition (FRC)

·         Provide evidence that your 2013 FRC team used a belt on its competition robot

Submission of Scholarship Application Package

Your complete 2013 Gates FIRST Scholarship application package must be submitted online, no later than May 15, 2013, 11:59 p.m. MST. Scholarship application packages submitted after the deadline will not be considered. Download PDF application and requirements online at www.gates.com/FIRST.

Application package includes:

·         A completed Gates FIRST Scholarship online application

·         A one page or shorter answer to the Gates 2013 Challenge Question, uploaded as a Word doc, PDF or image file

·         A one page or shorter letter of recommendation from an adult mentor/coach on your FIRST team, confirming the use of a belt drive on the competition robot and your participation in the 2013 FRC season, uploaded as a Word doc, PDF or image file

Gates 2013 FIRST Scholarship Challenge Questions

Part I: Describe the belt drive application on your robot. What advantages did it offer in solving the application challenge?

Part II: Gates belt drives can be found in everything from agricultural equipment, to zoom camera lenses, to now bicycles. Describe how Gates powers progress and impacts your everyday life.