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- Anti Backlash Machine Screwjack Actuator, 0.25t to 150t
Anti Backlash Control
Even the best manufacturing processes produce clearances between a screw and a mating nut.
In applications where loads may be in either direction, backlash can result from these clearances creating unacceptable movement in the controlled mechanism as loads change.
These applications are common in the paper, plastic, film, sheet metal forming processes, satellite, or other load-reversing applications, such applications may be subjected to extreme vibrations.
These vibrations can produce constant movement between the screw and lifting nut which can hammer the threads and cause premature wear.
To reduce this screw-to-nut backlash to an absolute minimum, Anti-Backlash actuators were developed.
The design allows the backlash to be adjusted to the minimum value practical. As wear occurs, the actuator can be easily adjusted, without any disassembly, to return the backlash to its original minimum value.
Key Adaptor Dimensions for Anti-Backlash Actuators

Actuator Capacity (tons) | Upright A Dia. (in) | Upright B (in) | Upright C (in) | Inverted D Dia. (in) | Inverted E (in) | Inverted F (in) |
1/4 & 1/2 | 1.66 | Pipe Length | 2.38 | 1.25 | .81 | 2.88 |
1 | 1.66 | .75 | 3.84 | 1.50 | .38 | 3.38 |
2 | 2.25 | 1.25 | 3.88 | 2.25 | .63 | 3.88 |
3 | 2.25 | 1.25 | 4.34 | 2.25 | .63 | 4.34 |
5 | 2.75 | 1.75 | 5.44 | 2.75 | .88 | 5.44 |
10 | 3.38 | 2.00 | 5.75 | 3.38 | 1.13 | 5.75 |
15 | 3.63 | 2.00 | 6.13 | 3.63 | 1.25 | 6.13 |
20 | 4.00 | 1.50 | 7.75 | 4.00 | 1.00 | 7.75 |
25 | 5.50 | 2.25 | 9.69 | 5.50 | 1.25 | 9.69 |
35 | 6.50 | 2.38 | 9.44 | 6.50 | 1.25 | 9.44 |
50 | 7.00 | 3.00 | 11.75 | 7.00 | 3.00 | 11.75 |
Anti-Backlash Machine Screw Actuators Performance Specifications
Capacity (tons) | 1/4 | 1/2 | 1 | 2 | 3 | 5 | 10 | 15 | 20 | 25 | 35 | 50 | 75 | 100 | 150 | |
Max. Speed Cface Driven (in/min)** | - | - | - | 72.0 | 72.0 | 108.0 | 108.0 | 108.0 | 108.0 | 107.5 | 107.5 | - | - | - | - | |
Max. Speed Red. Driven (in/Min)** | - | - | - | 14.4 | 14.14 | 21.9 | 21.9 | 21.9 | 21.9 | 22.2 | 22.4 | 12.2 | - | - | - | |
Lifting Screw | Diameter (in) | 1/2 | 5/8 | 3/4 | 1 | 1 | 1 1/2 | 2 | 2 1/4 | 2 1/2 | 3 | 3 3/4 | 4 1/2 | 5 | 6 | 7 |
Pitch (in) | 0.250 | 0.125 | 0.200 | 0.250 | 0.250 | 0.375 | 0.500 | 0.500 | 0.500 | 0.66 | 0.66 | 0.66 | 0.66 | 0.750 | 1.000 | |
Type | ACME | ACME | ACME | ACME | ACME | ACME | ACME | ACME | ACME | ACME | ACME | Mod.Sq. | Mod.Sq. | Mod.Sq. | Mod.Sq. | |
Worm Gear Ratios | Standard | 5:1 | 5:1 | 5:1 | 6:1 | 6:1 | 6:1 | 8:1 | 8:1 | 8:1 |
10 2/3:1 | 10 2/3:1 | 10 2/3:1 | 10 2/3:1 | 12:1 | 12:1 |
Optional Number 1 | - | - | 20:1 | 24:1 | 24:1 | 24:1 | 24:1 | 24:1 | 24:1 | 32:1 | 32:1 | 32:1 | 36:1 | 36:1 | 36:1 | |
Optional Number 2 | - | - | - | 12:1 | 12:1 | 12:1 | - | - | - | - | - | - | - | - | - | |
Turns of Worm for 1" Stroke | Standard | 20 | 40 | 25 | 24 | 24 | 16 | 16 | 16 | 16 | 16 | 16 | 16 | 16 | 16 | 12 |
Optional Number 1 | - | - | 100 | 96 | 96 | 64 | 48 | 48 | 48 | 48 | 48 | 48 | 48 | 48 | 36 | |
Optional Number 2 | - | - | - | 48 | 48 | 32 | - | - | - | - | - | - | - | - | - | |
Worm Torque and No Load (in-lb) | Standard | 2 | 2 | 5 | 5 | 5 | 10 | 20 | 20 | 30 | 40 | 50 | 100 | 150 | 200 | 250 |
Optional Number 1 | - | - | 5 | 5 | 5 | 10 | 20 | 20 | 30 | 40 | 50 | 100 | 150 | 200 | 250 | |
Optional Number 2 | - | - | 5 | 5 | 10 | - | - | - | - | - | - | - | - | - | - | |
Maximum Horsepower per Actuator | Standard | 1/3 | 1/3 | 1/2 | 2 | 2 | 4 | 5 | 5 | 5 | 8 | 8 | 15 | 15 | 25 | 25 |
Optional Number 1 | - | - | 1/4 | 1/2 | 3/4 | 3/4 | 1 1/2 | 1 1/2 | 1 1/2 | 2 1/2 | 2 1/2 | 6 | 6 | 11 | 11 | |
Optional Number 2 | - | - | - | 3/4 | 1 1/4 | 2 | - | - | - | - | - | - | - | - | - | |
Worm Torque Power at Full Load (in-lb) | Standard | 14 | 23 | 61 | 132 | 181 | 495 | 825 | 1573 | 2255 | 2970 | 4400 | 8250 | 13200 | 17600 | 30921 |
Optional Number 1 | - | - | 28 | 55 | 82 | 204 | 440 | 902 | 1287 | 1870 | 2640 | 4620 | 7095 | 9460 | 17050 | |
Optional Number 2 | - | - | - | 82 | 115 | 303 | - | - | - | - | - | - | - | - | - | |
Efficiency Rating (%) | Standard | 27.8 | 17.2 | 21.0 | 20.1 | 22.0 | 20.1 | 24.1 | 19.0 | 17.6 | 16.7 | 15.8 | 12.1 | 11.3 | 11.3 | 12.9 |
Optional Number 1 | - | - | 11.6 | 12.1 | 12.1 | 12.2 | 15.1 | 11.0 | 10.3 | 8.9 | 8.8 | 7.2 | 7.0 | 7.0 | 7.8 | |
Optional Number 2 | - | - | - | 16.1 | 17.2 | 16.4 | - | - | - | - | - | - | - | - | - | |
Weight with 6" Stroke (raise) (lb) | 2.3 | 2.3 | 5 | 17 | 17 | 35 | 52 | 66 | 93 | 160 | 240 | 410 | 1200 | 1200 | 1350 | |
Weight per Additional 1" Stroke (raise) (lb) | 0.1 | 0.1 | 0.3 | 0.3 | 0.3 | 0.9 | 1.4 | 1.5 | 2.6 | 2.5 | 3.7 | 5.5 | 9.0 | 9.0 | 12.6 | |
Key Torque (in-lb) | 40 | 70 | 175 | 460 | 670 | 1750 | 4700 | 7580 | 10625 | 14000 | 26500 | 47110 | 88650 | 118200 | 216000 | |
Max Worm Speed at Full Load (rpm) | Standard | 1469 | 909 | 521 | 955 | 696 | 509 | 382 | 200 | 140 | 170 | 115 | 115 | 72 | 90 | 51 |
Optional Number 1 | - | - | 573 | 573 | 573 | 232 | 215 | 105 | 73 | 84 | 60 | 82 | 53 | 73 | 41 | |
Optional Number 2 | - | - | - | 573 | 682 | 416 | - | - | - | - | - | - | - | - | - | |
Max Load at Full Horsepower and 1750 rpm (lb) | Standard | 407 | 474 | 469 | 2112 | 2285 | 2764 | 3978 | 3092 | 2698 | 4234 | 3832 | 5402 | 4485 | 8050 | 6361 |
Optional Number 1 | - | - | 356 | 1041 | 1705 | 879 | 1620 | 1157 | 764 | 1367 | 1082 | 2568 | 1427 | 4237 | 2610 | |
Optional Number 2 | - | - | - | 1136 | 2174 | 2119 | - | - | - | - | - | - | - | - | - |
Stainless Steel Anti-Backlash Actuators Performance Specifications
Capacity (tons) - 17-4PH Worm | 2 | 5 | 10 | 15 | 20 | 25 | 35 | 50 | 100 | |
Capacity (tons) - 316 SS Worm | 0.67 | 1.66 | 3.33 | 5.00 | 6.66 | 8.33 | 11.66 | 16.66 | 33.33 | |
Lifting Screw | Diameter (in) | 1 |
1 1/2 |
2 |
2 1/4 |
2 1/2 |
3 |
3 3/4 |
4 1/2 |
6 |
Pitch (in) | 0.250 |
0.375 |
0.500 |
0.500 |
0.500 |
0.666 |
0.666 |
0.666 |
0.750 |
|
Type | ACME | ACME |
ACME |
ACME |
ACME |
ACME |
ACME |
Mod.Sq. |
Mod.Sq. |
|
Worm Gear Ratios | Standard | 6:1 | 6:1 |
8:1 |
8:1 |
8:1 |
10 2/3:1 |
10 2/3:1 | 10 2/3:1 | 12:1 |
Optional Number 1 | 24:1 |
24:1 |
24:1 |
24:1 |
24:1 |
32:1 |
32:1 |
32:1 |
36:1 |
|
Optional Number 2 | 12:1 | 12:1 |
- |
- |
- |
- |
- |
- |
- |
|
Turns of Worm for 1" Raise | Standard | 24 | 16 |
16 | 16 |
16 | 16 |
16 | 16 | 16 |
Optional Number 1 | 96 | 64 | 48 |
48 |
48 |
48 |
48 |
48 |
48 |
|
Optional Number 2 | 48 | 32 |
- |
- |
- |
- |
- |
- |
- |
|
Worm Torque at No Load (in-lb) | Standard | 5 |
10 |
20 |
20 |
30 |
40 |
50 |
100 |
200 |
Optional Number 1 | 5 | 10 |
20 |
20 |
30 |
40 |
50 |
100 |
200 |
|
Optional Number 2 | 5 | 10 |
- |
- |
- |
- |
- |
- |
- |
|
Maximum Horsepower per Actuator | Standard | 2 | 4 |
5 |
5 |
5 |
8 |
8 |
15 |
25 |
Optional Number 1 | 1/2 | 3/4 |
1 1/2 |
1 1/2 |
1 1/2 |
2 1/2 |
2 1/2 |
6 |
11 |
|
Optional Number 2 | 3/4 | 2 |
- |
- |
- |
- |
- |
- |
- |
|
Worm Torque at Full Load (in-lb) 17-4PH Worm | Standard | 120 | 450 |
750 |
1430 |
2050 |
2700 |
4000 |
7500 |
16000 |
Optional Number 1 | 50 | 185 |
400 |
820 |
1170 |
1700 |
2400 |
4200 |
8600 |
|
Optional Number 2 | 75 | 275 |
- |
- |
- |
- |
- |
- |
- |
|
Worm Torque at Full Load (in-lb) 316SS Worm | Standard | 43 | 156 | 263 | 490 | 703 | 926 |
1366 |
2566 |
5466 |
Optional Number 1 | 20 | 68 |
147 |
287 |
410 |
593 |
833 |
1466 |
3000 |
|
Optional Number 2 | 28 |
98 |
- |
- |
- |
- |
- |
- |
- | |
Efficiency Rating (%) | Standard | 20.4 | 21.2 | 25.2 | 20.3 | 18.9 | 17.9 |
17.0 |
12.9 |
12.1 |
Optional Number 1 | 11.1 |
12.1 |
15.1 |
11.6 |
10.8 |
9.3 | 9.3 |
7.5 |
7.4 |
|
Optional Number 2 | 15.6 | 16.8 | - |
- |
- |
- |
- |
- |
- |
|
Weight with 6" Raise (lb) | 17 | 35 | 52 | 66 | 93 | 160 | 240 |
410 |
1200 |
|
Weight per Additional 1" Raise (lb) | 0.3 | 0.9 | 1.4 | 1.5 | 2.6 | 2.5 |
3.7 |
5.5 |
9.0 |
|
Key Torque (in-lb) | 153 |
581 |
1565 |
2527 |
3538 |
4665 |
8828 |
15697 |
39396 |
|
Max Worm Speed at Full Load (rpm) | Standard | 1750 | 1615 |
1198 |
643 |
449 |
544 |
369 |
368 |
288 |
Optional Number 1 | 1576 | 694 | 645 |
330 |
231 |
266 |
189 |
258 |
231 |
|
Optional Number 2 | 1669 | 1286 |
- |
- |
- |
- |
- |
- |
- |
|
Max Load at Full Horsepower and 1750 rpm (lb) | Standard | 1333 | 3047 |
4386 |
3406 |
2972 |
4664 |
4220 |
5949 |
8865 |
Optional Number 1 | 1156 | 972 |
1791 |
1276 |
843 |
1507 |
1192 |
2831 |
4671 |
|
Optional Number 2 | 1258 | 2339 | - |
- | - | - | - | - | - |

How it Works
When the screw (1) is under a compression load, the bottom of its thread surfaces are supported by the top thread surfaces of the worm gear (2). The anti-backlash nut (3), being pinned to the worm gear and floating on these pins and being adjusted downwards by the shell cap, forcing its bottom thread surfaces against the upper thread surfaces of the lifting screw at point (B).Thus backlash between the worm gear threadsand the lifting screw threads is reduced to a regulated minimum.
When wear occurs in the worm gear threads and the anti-backlash nut thread, the load carrting thickness of the worm gear thread will be reduced. This wear will create a gap at point (B) and provide backlash equal to the wear on the threads.
Under a compression load, the lifting screw will no longer be in contact with the lower thread surface of the anti-backlash nut. Under this condition, backlash will be present when a tension load is applied. The anti backlash feature can be maintained simply by adjusting the shell cap until the desired amount of backlash reduction is achieved. This will reduce the separation (A) between the anti- backlash nut and the worm gear and will reduce the backlash between the worm gear threads and the lifting screw to the desired minimum value.
To avoid binding and excessive wear, do not adjust lifting screw backlash to less than .0005".
When separation (A) has been reduced to zero, the wear limit has been reached.
Replace the worn gear and backlash nut set at this point.
This feature acts as a built in safety device.
Anti Backlash Control
Even the best manufacturing processes produce clearances between a screw and a mating nut.
In applications where loads may be in either direction, backlash can result from these clearances creating unacceptable movement in the controlled mechanism as loads change.
These applications are common in the paper, plastic, film, sheet metal forming processes, satellite, or other load-reversing applications, such applications may be subjected to extreme vibrations.
These vibrations can produce constant movement between the screw and lifting nut which can hammer the threads and cause premature wear.
To reduce this screw-to-nut backlash to an absolute minimum, Anti-Backlash actuators were developed.
The design allows the backlash to be adjusted to the minimum value practical. As wear occurs, the actuator can be easily adjusted, without any disassembly, to return the backlash to its original minimum value.
Key Adaptor Dimensions for Anti-Backlash Actuators

Actuator Capacity (tons) | Upright A Dia. (in) | Upright B (in) | Upright C (in) | Inverted D Dia. (in) | Inverted E (in) | Inverted F (in) |
1/4 & 1/2 | 1.66 | Pipe Length | 2.38 | 1.25 | .81 | 2.88 |
1 | 1.66 | .75 | 3.84 | 1.50 | .38 | 3.38 |
2 | 2.25 | 1.25 | 3.88 | 2.25 | .63 | 3.88 |
3 | 2.25 | 1.25 | 4.34 | 2.25 | .63 | 4.34 |
5 | 2.75 | 1.75 | 5.44 | 2.75 | .88 | 5.44 |
10 | 3.38 | 2.00 | 5.75 | 3.38 | 1.13 | 5.75 |
15 | 3.63 | 2.00 | 6.13 | 3.63 | 1.25 | 6.13 |
20 | 4.00 | 1.50 | 7.75 | 4.00 | 1.00 | 7.75 |
25 | 5.50 | 2.25 | 9.69 | 5.50 | 1.25 | 9.69 |
35 | 6.50 | 2.38 | 9.44 | 6.50 | 1.25 | 9.44 |
50 | 7.00 | 3.00 | 11.75 | 7.00 | 3.00 | 11.75 |
Anti-Backlash Machine Screw Actuators Performance Specifications
Capacity (tons) | 1/4 | 1/2 | 1 | 2 | 3 | 5 | 10 | 15 | 20 | 25 | 35 | 50 | 75 | 100 | 150 | |
Max. Speed Cface Driven (in/min)** | - | - | - | 72.0 | 72.0 | 108.0 | 108.0 | 108.0 | 108.0 | 107.5 | 107.5 | - | - | - | - | |
Max. Speed Red. Driven (in/Min)** | - | - | - | 14.4 | 14.14 | 21.9 | 21.9 | 21.9 | 21.9 | 22.2 | 22.4 | 12.2 | - | - | - | |
Lifting Screw | Diameter (in) | 1/2 | 5/8 | 3/4 | 1 | 1 | 1 1/2 | 2 | 2 1/4 | 2 1/2 | 3 | 3 3/4 | 4 1/2 | 5 | 6 | 7 |
Pitch (in) | 0.250 | 0.125 | 0.200 | 0.250 | 0.250 | 0.375 | 0.500 | 0.500 | 0.500 | 0.66 | 0.66 | 0.66 | 0.66 | 0.750 | 1.000 | |
Type | ACME | ACME | ACME | ACME | ACME | ACME | ACME | ACME | ACME | ACME | ACME | Mod.Sq. | Mod.Sq. | Mod.Sq. | Mod.Sq. | |
Worm Gear Ratios | Standard | 5:1 | 5:1 | 5:1 | 6:1 | 6:1 | 6:1 | 8:1 | 8:1 | 8:1 |
10 2/3:1 | 10 2/3:1 | 10 2/3:1 | 10 2/3:1 | 12:1 | 12:1 |
Optional Number 1 | - | - | 20:1 | 24:1 | 24:1 | 24:1 | 24:1 | 24:1 | 24:1 | 32:1 | 32:1 | 32:1 | 36:1 | 36:1 | 36:1 | |
Optional Number 2 | - | - | - | 12:1 | 12:1 | 12:1 | - | - | - | - | - | - | - | - | - | |
Turns of Worm for 1" Stroke | Standard | 20 | 40 | 25 | 24 | 24 | 16 | 16 | 16 | 16 | 16 | 16 | 16 | 16 | 16 | 12 |
Optional Number 1 | - | - | 100 | 96 | 96 | 64 | 48 | 48 | 48 | 48 | 48 | 48 | 48 | 48 | 36 | |
Optional Number 2 | - | - | - | 48 | 48 | 32 | - | - | - | - | - | - | - | - | - | |
Worm Torque and No Load (in-lb) | Standard | 2 | 2 | 5 | 5 | 5 | 10 | 20 | 20 | 30 | 40 | 50 | 100 | 150 | 200 | 250 |
Optional Number 1 | - | - | 5 | 5 | 5 | 10 | 20 | 20 | 30 | 40 | 50 | 100 | 150 | 200 | 250 | |
Optional Number 2 | - | - | 5 | 5 | 10 | - | - | - | - | - | - | - | - | - | - | |
Maximum Horsepower per Actuator | Standard | 1/3 | 1/3 | 1/2 | 2 | 2 | 4 | 5 | 5 | 5 | 8 | 8 | 15 | 15 | 25 | 25 |
Optional Number 1 | - | - | 1/4 | 1/2 | 3/4 | 3/4 | 1 1/2 | 1 1/2 | 1 1/2 | 2 1/2 | 2 1/2 | 6 | 6 | 11 | 11 | |
Optional Number 2 | - | - | - | 3/4 | 1 1/4 | 2 | - | - | - | - | - | - | - | - | - | |
Worm Torque Power at Full Load (in-lb) | Standard | 14 | 23 | 61 | 132 | 181 | 495 | 825 | 1573 | 2255 | 2970 | 4400 | 8250 | 13200 | 17600 | 30921 |
Optional Number 1 | - | - | 28 | 55 | 82 | 204 | 440 | 902 | 1287 | 1870 | 2640 | 4620 | 7095 | 9460 | 17050 | |
Optional Number 2 | - | - | - | 82 | 115 | 303 | - | - | - | - | - | - | - | - | - | |
Efficiency Rating (%) | Standard | 27.8 | 17.2 | 21.0 | 20.1 | 22.0 | 20.1 | 24.1 | 19.0 | 17.6 | 16.7 | 15.8 | 12.1 | 11.3 | 11.3 | 12.9 |
Optional Number 1 | - | - | 11.6 | 12.1 | 12.1 | 12.2 | 15.1 | 11.0 | 10.3 | 8.9 | 8.8 | 7.2 | 7.0 | 7.0 | 7.8 | |
Optional Number 2 | - | - | - | 16.1 | 17.2 | 16.4 | - | - | - | - | - | - | - | - | - | |
Weight with 6" Stroke (raise) (lb) | 2.3 | 2.3 | 5 | 17 | 17 | 35 | 52 | 66 | 93 | 160 | 240 | 410 | 1200 | 1200 | 1350 | |
Weight per Additional 1" Stroke (raise) (lb) | 0.1 | 0.1 | 0.3 | 0.3 | 0.3 | 0.9 | 1.4 | 1.5 | 2.6 | 2.5 | 3.7 | 5.5 | 9.0 | 9.0 | 12.6 | |
Key Torque (in-lb) | 40 | 70 | 175 | 460 | 670 | 1750 | 4700 | 7580 | 10625 | 14000 | 26500 | 47110 | 88650 | 118200 | 216000 | |
Max Worm Speed at Full Load (rpm) | Standard | 1469 | 909 | 521 | 955 | 696 | 509 | 382 | 200 | 140 | 170 | 115 | 115 | 72 | 90 | 51 |
Optional Number 1 | - | - | 573 | 573 | 573 | 232 | 215 | 105 | 73 | 84 | 60 | 82 | 53 | 73 | 41 | |
Optional Number 2 | - | - | - | 573 | 682 | 416 | - | - | - | - | - | - | - | - | - | |
Max Load at Full Horsepower and 1750 rpm (lb) | Standard | 407 | 474 | 469 | 2112 | 2285 | 2764 | 3978 | 3092 | 2698 | 4234 | 3832 | 5402 | 4485 | 8050 | 6361 |
Optional Number 1 | - | - | 356 | 1041 | 1705 | 879 | 1620 | 1157 | 764 | 1367 | 1082 | 2568 | 1427 | 4237 | 2610 | |
Optional Number 2 | - | - | - | 1136 | 2174 | 2119 | - | - | - | - | - | - | - | - | - |
Stainless Steel Anti-Backlash Actuators Performance Specifications
Capacity (tons) - 17-4PH Worm | 2 | 5 | 10 | 15 | 20 | 25 | 35 | 50 | 100 | |
Capacity (tons) - 316 SS Worm | 0.67 | 1.66 | 3.33 | 5.00 | 6.66 | 8.33 | 11.66 | 16.66 | 33.33 | |
Lifting Screw | Diameter (in) | 1 |
1 1/2 |
2 |
2 1/4 |
2 1/2 |
3 |
3 3/4 |
4 1/2 |
6 |
Pitch (in) | 0.250 |
0.375 |
0.500 |
0.500 |
0.500 |
0.666 |
0.666 |
0.666 |
0.750 |
|
Type | ACME | ACME |
ACME |
ACME |
ACME |
ACME |
ACME |
Mod.Sq. |
Mod.Sq. |
|
Worm Gear Ratios | Standard | 6:1 | 6:1 |
8:1 |
8:1 |
8:1 |
10 2/3:1 |
10 2/3:1 | 10 2/3:1 | 12:1 |
Optional Number 1 | 24:1 |
24:1 |
24:1 |
24:1 |
24:1 |
32:1 |
32:1 |
32:1 |
36:1 |
|
Optional Number 2 | 12:1 | 12:1 |
- |
- |
- |
- |
- |
- |
- |
|
Turns of Worm for 1" Raise | Standard | 24 | 16 |
16 | 16 |
16 | 16 |
16 | 16 | 16 |
Optional Number 1 | 96 | 64 | 48 |
48 |
48 |
48 |
48 |
48 |
48 |
|
Optional Number 2 | 48 | 32 |
- |
- |
- |
- |
- |
- |
- |
|
Worm Torque at No Load (in-lb) | Standard | 5 |
10 |
20 |
20 |
30 |
40 |
50 |
100 |
200 |
Optional Number 1 | 5 | 10 |
20 |
20 |
30 |
40 |
50 |
100 |
200 |
|
Optional Number 2 | 5 | 10 |
- |
- |
- |
- |
- |
- |
- |
|
Maximum Horsepower per Actuator | Standard | 2 | 4 |
5 |
5 |
5 |
8 |
8 |
15 |
25 |
Optional Number 1 | 1/2 | 3/4 |
1 1/2 |
1 1/2 |
1 1/2 |
2 1/2 |
2 1/2 |
6 |
11 |
|
Optional Number 2 | 3/4 | 2 |
- |
- |
- |
- |
- |
- |
- |
|
Worm Torque at Full Load (in-lb) 17-4PH Worm | Standard | 120 | 450 |
750 |
1430 |
2050 |
2700 |
4000 |
7500 |
16000 |
Optional Number 1 | 50 | 185 |
400 |
820 |
1170 |
1700 |
2400 |
4200 |
8600 |
|
Optional Number 2 | 75 | 275 |
- |
- |
- |
- |
- |
- |
- |
|
Worm Torque at Full Load (in-lb) 316SS Worm | Standard | 43 | 156 | 263 | 490 | 703 | 926 |
1366 |
2566 |
5466 |
Optional Number 1 | 20 | 68 |
147 |
287 |
410 |
593 |
833 |
1466 |
3000 |
|
Optional Number 2 | 28 |
98 |
- |
- |
- |
- |
- |
- |
- | |
Efficiency Rating (%) | Standard | 20.4 | 21.2 | 25.2 | 20.3 | 18.9 | 17.9 |
17.0 |
12.9 |
12.1 |
Optional Number 1 | 11.1 |
12.1 |
15.1 |
11.6 |
10.8 |
9.3 | 9.3 |
7.5 |
7.4 |
|
Optional Number 2 | 15.6 | 16.8 | - |
- |
- |
- |
- |
- |
- |
|
Weight with 6" Raise (lb) | 17 | 35 | 52 | 66 | 93 | 160 | 240 |
410 |
1200 |
|
Weight per Additional 1" Raise (lb) | 0.3 | 0.9 | 1.4 | 1.5 | 2.6 | 2.5 |
3.7 |
5.5 |
9.0 |
|
Key Torque (in-lb) | 153 |
581 |
1565 |
2527 |
3538 |
4665 |
8828 |
15697 |
39396 |
|
Max Worm Speed at Full Load (rpm) | Standard | 1750 | 1615 |
1198 |
643 |
449 |
544 |
369 |
368 |
288 |
Optional Number 1 | 1576 | 694 | 645 |
330 |
231 |
266 |
189 |
258 |
231 |
|
Optional Number 2 | 1669 | 1286 |
- |
- |
- |
- |
- |
- |
- |
|
Max Load at Full Horsepower and 1750 rpm (lb) | Standard | 1333 | 3047 |
4386 |
3406 |
2972 |
4664 |
4220 |
5949 |
8865 |
Optional Number 1 | 1156 | 972 |
1791 |
1276 |
843 |
1507 |
1192 |
2831 |
4671 |
|
Optional Number 2 | 1258 | 2339 | - |
- | - | - | - | - | - |

How it Works
When the screw (1) is under a compression load, the bottom of its thread surfaces are supported by the top thread surfaces of the worm gear (2). The anti-backlash nut (3), being pinned to the worm gear and floating on these pins and being adjusted downwards by the shell cap, forcing its bottom thread surfaces against the upper thread surfaces of the lifting screw at point (B).Thus backlash between the worm gear threadsand the lifting screw threads is reduced to a regulated minimum.
When wear occurs in the worm gear threads and the anti-backlash nut thread, the load carrting thickness of the worm gear thread will be reduced. This wear will create a gap at point (B) and provide backlash equal to the wear on the threads.
Under a compression load, the lifting screw will no longer be in contact with the lower thread surface of the anti-backlash nut. Under this condition, backlash will be present when a tension load is applied. The anti backlash feature can be maintained simply by adjusting the shell cap until the desired amount of backlash reduction is achieved. This will reduce the separation (A) between the anti- backlash nut and the worm gear and will reduce the backlash between the worm gear threads and the lifting screw to the desired minimum value.
To avoid binding and excessive wear, do not adjust lifting screw backlash to less than .0005".
When separation (A) has been reduced to zero, the wear limit has been reached.
Replace the worn gear and backlash nut set at this point.
This feature acts as a built in safety device.
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