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Information courtesy:
Backstop Applications
The Falk NRT backstop is designed to prevent reverse rotation in applications such as inclined conveyors, bucket elevators, fans, rotary pumps and kilns. If local safety codes permit, the backstop may be used as a backup for a brake on those applications, but NOT in people conveying systems such as elevators, manlifts, ski tows or ski lifts. Also DO NOT use the backstop as a substitute for a brake.
Indexing
Falk NRT Backstops can be used for indexing service. Refer application data to the Factory for selection.
Safety Standards
The backstop and normal associated equipment (shaft, pulleys, etc.) involve moving parts, therefore consult local, state, OSHA and ANSI safety codes for proper guarding of revolving parts and possible pinch points. (A pinch point occurs at the contact point between the backstop torque arm and support, and between the torque arm and stirrup.
Chemical Atmospheres
The backstop may be damaged if exposed to certain types of chemicals or vapors; for example, potash dust, chlorine gas, carbon tetrachloride, etc. These materials may cause deterioration of the seals or aluminum roller cage rings.
Operating Temperatures
Enclosure of the backstop may cause overheating. Provide adequate ventilation. Backstop operating temperatures, at maximum overrunning speed, may reach 200'F (93'C). Determine the effect of this temperature on the driven equipment and provide cooling if necessary.
If a backstop operates in the sun at ambient temperatures over 100'F (38'C), then special measures should be taken to protect the backstop from solar energy. This protection can consist of a canopy over the backstop or reflective paint on the backstop. If neither is possible, a cooling device such as a fan may be required to prevent the sump temperature from exceeding the allowable maximum of 200'F (93'C).
Keys and Keyways
Keys used with NRT Backstops are furnished by Falk. Keys are either cold drawn 1045 steel or heat treated alloy steel (310-350 HB).
Do not use sled runner type keyway. It may induce undue forces on backstop.
| Backstop Size | Nominal Shaft Diameter (Over-Incl) |
Shaft Keyway | Key | ||
| Width * Depth | Key Length Furnished | Min. Key Engagement | |||
| 1075 | 1.9375 | .500 * .250 | 7.250 | 7.25 | 2 |
| 1.9375 - 2.2500 | .500 * .250 | 7.250 | 7.25 | 2 | |
| 2.2500 - 2.7500 | .625 * .312 | 6.000 | 6.00 | 2 | |
| 2.7500 - 3.2500 | .750 * .375 | 7.000 | 5.50 | 1 | |
| 3.2500 - 3.5000 | .875 * .437 | 5.500 | 4.00 | 1 | |
| 3.5000 - 3.7500 | .875 * .437 | 7.250 | 5.00 | 1 | |
| 3.7500 - 3.9375 | 1.000 * .500 | 7.000 | 5.00 | 1 | |
| 1085 | 2.9375 | .750 * .375 | 7.000 | 6.50 | 2 |
| 2.9375 * 3.2500 | .750 * .375 | 7.000 | 6.50 | 2 | |
| 3.2500 - 3.7500 | .875 * .437 | 5.500 | 5.00 | 2 | |
| 3.7500 - 4.5000 | 1.000 * .500 | 7.000 | 5.00 | 1 | |
| 4.5000 - 4.7500 | 1.250 * .625 | 7.000 | 3.50 | 1 | |
| 4.7500 - 5.1875 | 1.250 * .625 | 7.000 | 7.00 | 1 | |
| 1095 | 3.4375 | .875 * .437 | 9.000 | 8.00 | 2 |
| 3.4375 - 3.75 | .875 * .437 | 9.000 | 8.00 | 2 | |
| 3.7500 - 4.5000 | 1.000 * .500 | 9.000 | 8.50 | 1 | |
| 4.5000 - 5.0000 | 1.250 * .625 | 7.000 | 6.00 | 1 | |
| 5.0000 - 5.5000 | 1.250 * .625 | 7.000 | 6.50 | 1 | |
| 1105 | 4.9375 | 1.250 * .625 | 7.000 | 6.50 | 2 |
| 4.9375 - 5.5000 | 1.250 * .625 | 7.000 | 6.50 | 2 | |
| 5.5000 - 6.5000 | 1.500 * .750 | 8.000 | 6.50 | 1 | |
| 6.5000 - 7.4375 | 1.750 * .750 | 9.000 | 5.50 | 1 | |
| 1115 | 5.9375 | 1.500 * .750 | 8.000 | 7.50 | 2 |
| 5.9375 - 6.5000 | 1.500 * .750 | 8.000 | 7.50 | 2 | |
| 6.5000 - 7.5000 | 1.750 * .750 | 9.000 | 9.00 | 1 | |
| 7.5000 - 8.0000 | 2.000 * .750 | 9.000 | 8.00 | 1 | |
| 8.0000 - 8.4375 | 2.000 * .750 | 10.500 | 10.50 | 1 | |
| 1125 | 7.2500 | 1.750 * .750 | 11.000 | 11.00 | 1 |
| 7.2500 - 7.5000 | 1.750 * .750 | 11.000 | 11.00 | 1 | |
| 7.5000 - 9.0000 | 2.000 * .750 | 11.000 | 10.50 | 1 | |
| 1135 | 8.5000 | 2.000 * .750 | 11.000 | 10.00 | 2 |
| 8.5000 - 9.0000 | 2.000 * .750 | 11.000 | 10.00 | 2 | |
| 9.0000 - 10.5000 | 2.500 * .875 | 12.000 | 9.50 | 1 | |
| 1145 | 9.000 | 2.000 * .750 | 13.000 | 13.00 | 2 |
| 9.0000 - 11.0000 | 2.500 * .875 | 12.000 | 11.50 | 2 | |
| 11.0000 - 12.0000 | 3.000 * 1.000 | 13.000 | 11.00 | 1 | |
| 1155 | 10.5000 | 2.500 * 1.250 | 12.000 | 11.00 | 2 |
| 10.5000 - 11.0000 | 2.500 * 1.25 | 12.000 | 11.00 | 2 | |
| 11.0000 - 13.0000 | 3.000 * 1.000 | 13.000 | 13.00 | 2 | |
| 13.0000 - 13.2500 | 3.500 * 1.250 | 12.000 | 9.00 | 2 | |
| 1165 | 12.5000 | 3.000 * 1.000 | 15.500 | 12.00 | 2 |
| 12.5000 - 13.0000 | 3.000 * 1.000 | 15.500 | 12.00 | 2 | |
| 13.0000 - 15.0000 | 3.500 * 1.250 | 12.000 | 12.00 | 2 | |
| 15.0000 - 15.5000 | 4.000 * 1.500 | 13.000 | 9.00 | 2 | |
| 1175 | 13.5000 | 3.500 * 1.250 | 16.000 | 15.50 | 2 |
| 13.5000 - 15.0000 | 3.500 * 1.250 | 16.000 | 15.50 | 2 | |
| 15.0000 - 17.5000 | 4.000 * 1.500 | 13.000 | 13.00 | 2 | |
| 1185 | 15.5000 | 4.000 * 1.500 | 17.000 | 13.50 | 2 |
| 15.5000 - 18.0000 | 4.000 * 1.500 | 17.000 | 13.50 | 2 | |
| 18.0000 - 20.0000 | 5.000 * 1.750 | 14.000 | 13.50 | 2 | |
| Nominal Diameter (From-Incl) |
Nominal Shaft Tolerance |
Nominal Bore Diameter Tolerance |
Bore-Shafts Min-Max Clearance |
| 1.9375 - 2.9375 | +.0000 -.0005 | +.0005 +.0015 | .0005 - .0020 |
| 3.0000 - 7.9375 | +.0000 -.0010 | +.0010 +.0025 | .0010 - .0035 |
| 8.0000 - 11.9375 | +.0000 -.0010 | +.0015 +.0035 | .0015 - .0045 |
| 12.0000 - 14.9375 | +.0000 -.0010 | +.0020 +.0045 | .0020 - .0055 |
| 15.0000 - 20.0000 | +.0000 -.0020 | +.0020 +.0045 | .0020 - .0065 |
Backstop Mounting Positions
The supporting shaft must be horizontal within 5deg. The backstop-torque arm assembly may be rotated to any angular position, but the position must be specified by the purchaser to permit Folk to furnish oil lines to suit the mounting.
The symmetrical backstop design permits turning the backstop end for end to provide either direction of shaft rotation.
The backstop overrunning (or free rotation) direction is indicated by a rotation arrow on each side of the backstop. The purchaser is responsible for mounting the backstop retaining collar, oil line, oil level sight gauge and air vent and for furnishing the oil and the torque arm stirrup per the Falk service manual.
Torque Arm Stirrups
Locate torque arm stirrup at .9N as illustrated at right. Design the stirrup to withstand the Torque Arm Reaction Force listed in Table 3. If the stirrup must be located closer, design the stirrup to withstand the force developed by the actual torque applied to the backstop. Use the following formula to determine the force.
Actual Reaction Force = Drive Pulley Peak Torque / Actual Application Dimension N
The torque arm must be free to move within the stirrup. Provide clearance on three sides as shown at right. DO NOT restrict torque arm movement by welding or securing to any supporting structure.
Locate the torque arm support surface parallel (deg) to the axis of the shaft on which the backstop is mounted.
A boot or hood is recommended for all positions of the torque arm to prevent accumulation of material around the torque arm stirrup. This also provides a guard against a possible pinch point. DO NOT restrict movement of the torque arm.
Grease Purged Seals
Refer to Page 3 for details.
The option of adding grease is the purchaser's. Adding grease to the seals is NOT RECOMMENDED if grease could contaminate the
material being processed as in the food and drug industries.
Refer to Manual 568-110 for a listing of trans-mission fluids, oils and greases that meet Falk specifications.
Stored or Inactive Backstops
Backstops are shipped without lubricant, but the one ounce of Motorstor* vapor phase rust inhibitor in the backup will protect the internal parts against rust for a period of six months.
If the backstop is to be stored or inactive for more than six months, add lubricant and Motorstor* as recommended in the service manual for every additional six month period. Indoor storage or a suitable covering is recommended.
If the backstop is to remain inoperative for extended periods of time, remove the load before shutting down. Refer to service manual for complete instructions.
| Backstop Size | Catalog Torque Rating | N (Inches) |
.9N .5" |
Torque Arm Reaction Force-lb |
| Pound-Feet | ||||
| 1075 | 10,000 | 36.0 | 32.5 | 5550 |
| 1085 | 16,000 | 48.0 | 43.0 | 6700 |
| 1095 | 28,000 | 54.0 | 48.0 | 10500 |
| 1105 | 45,000 | 66.0 | 59.5 | 13600 |
| 1115 | 75,000 | 72.0 | 65.0 | 20800 |
| 1125 | 105,000 | 78.0 | 70.0 | 27000 |
| 1135 | 150,000 | 82.0 | 74.0 | 36500 |
| 1145 | 212,000 | 88.0 | 79.0 | 48300 |
| 1155 | 249,000 | 94.0 | 84.0 | 53300 |
| 1165 | 346,000 | 100.0 | 90.0 | 69200 |
| 1175 | 519,000 | 120.0 | 108.0 | 86500 |
| 1185 | 747,000 | 120.0 | 108.0 | 124500 |
