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Application Guidelines

BC3 Application Guidelines
1. Cushion Needle Adjustment
BC3 Cushion Adjustment Photo
Adjust the cushion needles in the cylinder heads carefully to obtain a smooth, hesitation free deceleration for your particular application. If there are questions on proper adjustment, please contact Tolomatic, Inc.
2. Cushion Data Charts
NOTE: The velocities listed on the Cushion Data charts for the Band Cylinder models on this website are final or cushion impact velocities. On applications where the internal cushions are to be used, be sure the actual, final or impact velocity is known. If the velocity is not known, use of limit switches with valve deceleration circuits or shock absorbers should be considered.
3. Lubrication Guidelines
Application Guidelines-Example of Lubrication

All Tolomatic BC3 actuators are prelubricated at the factory with a high quality No. 2 lithium-soap base grease. Relubrication is recommended every 10 million linear feet using a lithium-soap base grease for optimal bearing performance. To relubricate, lift back upper sealing band and apply grease directly to the stationary ball ways. Applications that are exposed to moisture or dirt, may require more frequent relubrication.

To ensure maximum actuator life, the following guidelines should be followed:

  • Filtration: We recommend the use of dry, filtered air in our products. "Filtered air" means a level of 10 Micron or less. "Dry" means air should be free of appreciable amounts of moisture. Regular maintence of installed filters will generally keep excess moisture in check.
  • External Lubricators (optional): The factory prelubrication of Tolomatic actuators wil provide optimal performance without the use of external lubrication. However, external lubricators can further extend service life of pneumatic actuators if the supply is kept constant. Oil lubricators, (mist or drop) should supply a minimum of 1 drop per 20 standard cubic feet per minute to the cylinder. As a rule of thumb, double that rate if water in the system is suspected. Demanding conditions may require more lubricant. If lubricators are used, we recommend a non-detergent, 20cP @ 140oF 10-weight lubricant. Optimum conditions for standard cylinder operation is +32o to +150oF (+0o to 65.5oC). NOTE: Use of external lubricators may wash away the factory installed lubrication. External lubricants must be maintained in a constant supply or the result will be a dry actuator prone to premature wear.
  • Sanitary enviroments: Oil mist lubricators must dispense "Food Grade" lubricants to the air supply. Use fluids with ORAL LD50 toxicity ratings of 35 or higher such as Multitherm® PG-1 or equivalent. Demanding conditions can require a review of the application.

4. BC3 Deceleration Considerations
While the BC3 is capable of carrying very large loads, consideration must be given on how to stop the load at the end of stroke. If Tolomatic cushions or shocks are to be used, please stay within the performance guidelines for each actuator selected. If you should decide to utilize another type of shock absorber, be sure that the deceleration of the load is smooth and over adequate distance.
BC3: Application Guidelines Illustration

The example shown at right illustrates this:

Upon hitting the shock absorber, a load of 10 lbs. is traveling at a final velocity of 80 inches/second. It must be brought to rest over the shock absorber stroke of 0.50 inches. To determine the Mz and g forces on the carrier at this point:

Mz = moment about z-axis     V = velocity (final)     
a = deceleration rate
g    = 386.4 in/sec2 (standard gravity)    
s = shock stroke

     a = vf2      (80 in/sec)2 = 6400 in/sec2 (decel rate)
            2s      2 x 0.50 in.

     force equiv. = a x L = 6400 in/sec2 x 10 lbs = 165.6 lbs
                                 g          386.4 in/sec2

Therefore the Mz created during stopping is:
Mz = (force ea) x L = 165.6 lbs x 12 in. = 1987.2 in-lbs

Although an Mz = 1992 is over our catalog ratings, this is acceptable during stopping of the load if it is less than three (3) times the catalog rated moment load. However, moment values should never exceed 3 times catalog ratings during stopping. If this cannot be accomplished, then a deceleration circuit should be utilized.

5. Final Velocity Calculation
Application Guidelines Final Velocity Graph

Velocity calculations for all rodless cylinders need to differentiate between final velocity and average velocity. For example: Stroking a 100-inch BC2 model in one second yields an average velocity of 100 inches per second. To properly determine the initial forces for cushioning, it is important to know the final (or impact) velocity. Rodless cylinders accelerate and decelerate at each end of the stroke. Therefore this acceleration must be considered (see diagram at left).

If final (or impact) velocity cannot be calculated directly, a resonable guideline is to use 2 x average velocity.