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- Machine Screwjack Actuator, 1/4t to 1t
Machine Screw Jack
These screw actuators offer a positive mechanical action, precise positioning and uniform lifting speeds.
The standard configurations include, upright or inverted units with translating or rotating lifting screws, with top plates, threaded or clevis end fittings.
They can be controlled accurately for positioning within thousands of one inch.
Unevenly distributed loads can be lifted with uniform speeds.
All actuators are designed and built to be positive acting, giving accurate response to motive power.

Top Plate

Clevis End

Threaded end
Rotating Inverted Machine Screwjack Actuator

Model Number | Rating | A (in) | B (in) | C (in) | D (in) | F (in) | G (in) | H (in) | I (in) | J (in) | K (in) |
DM-2556 | 1/4 TON | Raise + 1 1/2 | 5 / 8 | 2 3/8 | 3 / 8 | 0.312 | 7 / 8 | 3 / 8 | 2 1/4 | 4 Holes- 9/32 Dia. on 1 3/4 Dia. B.C. | 1 |
DM-2626 | 1/2 TON |
Raise + 1 7/8 | 5 / 8 | 2 3/8 | 3 / 8 | 0.437 | 7 / 8 | 3 / 8 | 2 1/4 | 4 Holes- 9/32 Dia. on 1 3/4 Dia. B.C. | 1 |
DM-2502 | 1 TON | Raise + 1 3/4 | 5 / 8 |
3 1/4 | 1 / 4 | 0.500 |
1 1/2 | 1 1/2 | 1 1/2 | 4 Holes- 13/32 Dia. on 2 3/8 Dia. B.C. |
1 1/2 |
Rotating Upright Machine Screwjack Actuator

Model Number | Rating | A (in) | B (in) | C (in) | F (in) | G (in) | H (in) | I (in) | J (in) | K (in) |
UM-2556 | 1/4 Ton | Raise + 1 1/2 | 5 / 8 | 2 3/8 | 0.312 | 7 / 8 | 3 / 8 | 2 1/4 | 4 Holes- 9/32 Dia. on 1 3/4 Dia. B.C. | 1 |
UM-2626 |
1/2 Ton | Raise + 1 7/8 | 5 / 8 | 2 3/8 | 0.437 | 7 / 8 | 3 / 8 | 2 1/4 | 4 Holes- 9/32 Dia. on 1 3/4 Dia. B.C. | 1 |
UM-2502 | 1 Ton | Raise + 1 3/4 | 5 / 8 | 3 1/4 | 0.500 | 1 1/2 | 1 / 2 | 3 1/4 | 4 Holes-13/32 Dia. on 2 3/8 Dia. B.C. | 1 1/2 |
Rotating Screwjack Specifications
Standard Actuator Number | Upright | UM2556 | UM2626 | UM2502 |
Inverted | DM2556 | DM2626 | DM2502 | |
Special Actuator Number | Upright | UM3056 | UM3626 | UM3502 |
Inverted | DM3056 | DM3626 | DM3502 | |
Rated Load (lb) | 500 | 1000 | 2000 | |
Diameter of Lifting Screw (in) | 1/2 .250 Pitch ACME | 5/8 .125 Pitch ACME | 3/4 .200 Pitch ACME | |
Base Size (in) |
2 1/4 x 4 | 2 1/4 x 4 | 3 3/4 x5 | |
Worm Gear Ratios | Standard Ratio | 5:1 | 5:1 | 5:1 |
Optional | - | - | 20:1 | |
Turns of Worm for 1" Raise | Standard Ratio | 20 | 40 | 25 |
Optional | - | - | 100 | |
Maximum H.P Per Acutator | Standard Ratio | 1/3 | 1/3 | 1/2 |
Optional | - | - | 1/4 | |
Torque at Full Load* (in-lbs) | Standard Ratio | 13 | 21 | 55 |
Optional | - | - | 25 | |
Jack Efficiency Rating (%) | Standard Ratio | 33.0 | 20.0 | 24.5 |
Optional | - | - | 14.0 | |
Weight with Base Raise of 6" (lb) | 2.3 | 2.3 | 5.0 | |
Weight for Each Additional 1" Raise (lb) | 0.1 | 0.1 | 0.3 |
Translating Screwjack Specifications
Anti-Backlash | |||||||
Actutator Number | 2555 | 2625 | 2501 | 4555 | 4625 | 4501 | |
Rated Load (lb) | 500 | 1000 | 2000 | 500 | 1000 | 2000 | |
Diameter of Lifting Screw (in) | 1/2 .250 Pitch ACME | 5/8 .125 Pitch ACME | 3/4 .200 Pitch ACME | 1/2 .250 Pitch ACME | 5/8 .125 Pitch ACME | 3/4 .200 Pitch ACME | |
Closed Height* (in) | 4 | 4 | 4 1/2 | 4 | 4 | 5 | |
Base Size (in) | 2 1/4 x 4 | 2 1/4 x 4 | 2 3/4 x5 | 2 1/4 x 4 | 2 1/4 x 4 | 2 3/4 x 5 | |
Worm Gear Ratios | Standard Ratio | 5:1 | 5:1 | 5:1 | 5:1 | 5:1 | 5:1 |
Optional | - | - | 20:1 | - | - | 20:1 | |
Turns of Work for 1" Raise | Standard Ratio | 20 | 40 | 25 | 20 | 40 | 25 |
Optional | - | - | 100 | - | - | 100 | |
Maximum H.P. Per Actuator | Standard Ratio | 1/3 | 1/3 | 1/2 | 1/3 | 1/3 | 1/2 |
Optional | - | - | 1/4 | - | - | 1/4 | |
Torque at Full Load (in-lbs) | Standard Ratio | 13 | 21 | 55 | 15 | 23 | 60 |
Optional | - | - | 25 | - | - | 27 | |
Actuator Efficiency Rating (%) | Standard Ratio | 33 | 20 | 24.5 | 26.5 | 17.3 | 21.2 |
Optional | - | - | 14.0 | - | - | 11.8 | |
Weight with Base Raise of 6" (lb) | 2 1/4 | 2 1/4 | 5 | 2 1/2 | 2 1/2 | 6 | |
Weight for Each Additional 1" Raise (lb) | .10 | .10 | .27 | .10 | .10 | .27 |

Rotating Parts List
* Used on 1/4 and 1/2 ton only.
** Used on 1 ton only.
Index Number | Part Name | Quantity |
1 | Screw, Set | 2 |
2 | Cap, Shell | 1 |
3 | Shell, Unit | 1 |
4a | Expansion Plug | 1 |
5 | Screw, Lifting | 1 |
6 | Worm Gear | 1 |
7 | Bearing, Top Load | 1 |
8 |
Bearing, Bottom Load |
1 |
9* | Screw, Set | 4 |
10* | Bushing, Worm Retainer | 2 |
11 | Worm | 1 |
12* | Thrust Race | 4 |
13* | Bearing, Needle | 2 |
14 | Bushing, Guide | 1 |
15 | Fitting, Grease | 1 |
16 | Nameplate | 1 |
17** | Retainer Ring | 2 |
18** | Bearing, Worm | 2 |
19 | Screw, Drive | 2 |
20 | Lock Nut | 1 |
21* | Washer, Lock | 1 |
22 | Key | 1 |
23 | Lifting Nut | 1 |
Translating Parts List

* Used on 1/4 and 1/2 ton only.
** Used on 1 ton only.
Index Number | Part Name | Quantity |
1 | Screw, Set | 2 |
2 | Cap, Shell | 1 |
3 | Shell, Unit | 1 |
4 | Pipe, Bottom | 1 |
5 | Screw Assembly, Lifting | 1 |
6a | Worm Gear | 1 |
6b |
Backlash Nut Assembly (Mfg'd and sold in sets only) |
1 |
7 | Bearing, Top Load | 1 |
8 | Bearing, Bottom Load | 1 |
9* | Screw, Set | 4 |
10* | Bushing, Worm Retainer | 2 |
12* | Thrust Race | 4 |
13* | Bearing, Needle | 2 |
14 |
Bushing, Guide (inverted models only) |
1 |
15 | Fitting, Grease | 1 |
16 | Nameplate | 1 |
17** | Retainer Ring | 2 |
18** | Bearing, Worm | 2 |
19** | Drive Lock Pin, Top Plate | 1 |
Machine Screw Jack
These screw actuators offer a positive mechanical action, precise positioning and uniform lifting speeds.
The standard configurations include, upright or inverted units with translating or rotating lifting screws, with top plates, threaded or clevis end fittings.
They can be controlled accurately for positioning within thousands of one inch.
Unevenly distributed loads can be lifted with uniform speeds.
All actuators are designed and built to be positive acting, giving accurate response to motive power.

Top Plate

Clevis End

Threaded end
Rotating Inverted Machine Screwjack Actuator

Model Number | Rating | A (in) | B (in) | C (in) | D (in) | F (in) | G (in) | H (in) | I (in) | J (in) | K (in) |
DM-2556 | 1/4 TON | Raise + 1 1/2 | 5 / 8 | 2 3/8 | 3 / 8 | 0.312 | 7 / 8 | 3 / 8 | 2 1/4 | 4 Holes- 9/32 Dia. on 1 3/4 Dia. B.C. | 1 |
DM-2626 | 1/2 TON |
Raise + 1 7/8 | 5 / 8 | 2 3/8 | 3 / 8 | 0.437 | 7 / 8 | 3 / 8 | 2 1/4 | 4 Holes- 9/32 Dia. on 1 3/4 Dia. B.C. | 1 |
DM-2502 | 1 TON | Raise + 1 3/4 | 5 / 8 |
3 1/4 | 1 / 4 | 0.500 |
1 1/2 | 1 1/2 | 1 1/2 | 4 Holes- 13/32 Dia. on 2 3/8 Dia. B.C. |
1 1/2 |
Rotating Upright Machine Screwjack Actuator

Model Number | Rating | A (in) | B (in) | C (in) | F (in) | G (in) | H (in) | I (in) | J (in) | K (in) |
UM-2556 | 1/4 Ton | Raise + 1 1/2 | 5 / 8 | 2 3/8 | 0.312 | 7 / 8 | 3 / 8 | 2 1/4 | 4 Holes- 9/32 Dia. on 1 3/4 Dia. B.C. | 1 |
UM-2626 |
1/2 Ton | Raise + 1 7/8 | 5 / 8 | 2 3/8 | 0.437 | 7 / 8 | 3 / 8 | 2 1/4 | 4 Holes- 9/32 Dia. on 1 3/4 Dia. B.C. | 1 |
UM-2502 | 1 Ton | Raise + 1 3/4 | 5 / 8 | 3 1/4 | 0.500 | 1 1/2 | 1 / 2 | 3 1/4 | 4 Holes-13/32 Dia. on 2 3/8 Dia. B.C. | 1 1/2 |
Rotating Screwjack Specifications
Standard Actuator Number | Upright | UM2556 | UM2626 | UM2502 |
Inverted | DM2556 | DM2626 | DM2502 | |
Special Actuator Number | Upright | UM3056 | UM3626 | UM3502 |
Inverted | DM3056 | DM3626 | DM3502 | |
Rated Load (lb) | 500 | 1000 | 2000 | |
Diameter of Lifting Screw (in) | 1/2 .250 Pitch ACME | 5/8 .125 Pitch ACME | 3/4 .200 Pitch ACME | |
Base Size (in) |
2 1/4 x 4 | 2 1/4 x 4 | 3 3/4 x5 | |
Worm Gear Ratios | Standard Ratio | 5:1 | 5:1 | 5:1 |
Optional | - | - | 20:1 | |
Turns of Worm for 1" Raise | Standard Ratio | 20 | 40 | 25 |
Optional | - | - | 100 | |
Maximum H.P Per Acutator | Standard Ratio | 1/3 | 1/3 | 1/2 |
Optional | - | - | 1/4 | |
Torque at Full Load* (in-lbs) | Standard Ratio | 13 | 21 | 55 |
Optional | - | - | 25 | |
Jack Efficiency Rating (%) | Standard Ratio | 33.0 | 20.0 | 24.5 |
Optional | - | - | 14.0 | |
Weight with Base Raise of 6" (lb) | 2.3 | 2.3 | 5.0 | |
Weight for Each Additional 1" Raise (lb) | 0.1 | 0.1 | 0.3 |
Translating Screwjack Specifications
Anti-Backlash | |||||||
Actutator Number | 2555 | 2625 | 2501 | 4555 | 4625 | 4501 | |
Rated Load (lb) | 500 | 1000 | 2000 | 500 | 1000 | 2000 | |
Diameter of Lifting Screw (in) | 1/2 .250 Pitch ACME | 5/8 .125 Pitch ACME | 3/4 .200 Pitch ACME | 1/2 .250 Pitch ACME | 5/8 .125 Pitch ACME | 3/4 .200 Pitch ACME | |
Closed Height* (in) | 4 | 4 | 4 1/2 | 4 | 4 | 5 | |
Base Size (in) | 2 1/4 x 4 | 2 1/4 x 4 | 2 3/4 x5 | 2 1/4 x 4 | 2 1/4 x 4 | 2 3/4 x 5 | |
Worm Gear Ratios | Standard Ratio | 5:1 | 5:1 | 5:1 | 5:1 | 5:1 | 5:1 |
Optional | - | - | 20:1 | - | - | 20:1 | |
Turns of Work for 1" Raise | Standard Ratio | 20 | 40 | 25 | 20 | 40 | 25 |
Optional | - | - | 100 | - | - | 100 | |
Maximum H.P. Per Actuator | Standard Ratio | 1/3 | 1/3 | 1/2 | 1/3 | 1/3 | 1/2 |
Optional | - | - | 1/4 | - | - | 1/4 | |
Torque at Full Load (in-lbs) | Standard Ratio | 13 | 21 | 55 | 15 | 23 | 60 |
Optional | - | - | 25 | - | - | 27 | |
Actuator Efficiency Rating (%) | Standard Ratio | 33 | 20 | 24.5 | 26.5 | 17.3 | 21.2 |
Optional | - | - | 14.0 | - | - | 11.8 | |
Weight with Base Raise of 6" (lb) | 2 1/4 | 2 1/4 | 5 | 2 1/2 | 2 1/2 | 6 | |
Weight for Each Additional 1" Raise (lb) | .10 | .10 | .27 | .10 | .10 | .27 |

Rotating Parts List
* Used on 1/4 and 1/2 ton only.
** Used on 1 ton only.
Index Number | Part Name | Quantity |
1 | Screw, Set | 2 |
2 | Cap, Shell | 1 |
3 | Shell, Unit | 1 |
4a | Expansion Plug | 1 |
5 | Screw, Lifting | 1 |
6 | Worm Gear | 1 |
7 | Bearing, Top Load | 1 |
8 |
Bearing, Bottom Load |
1 |
9* | Screw, Set | 4 |
10* | Bushing, Worm Retainer | 2 |
11 | Worm | 1 |
12* | Thrust Race | 4 |
13* | Bearing, Needle | 2 |
14 | Bushing, Guide | 1 |
15 | Fitting, Grease | 1 |
16 | Nameplate | 1 |
17** | Retainer Ring | 2 |
18** | Bearing, Worm | 2 |
19 | Screw, Drive | 2 |
20 | Lock Nut | 1 |
21* | Washer, Lock | 1 |
22 | Key | 1 |
23 | Lifting Nut | 1 |
Translating Parts List

* Used on 1/4 and 1/2 ton only.
** Used on 1 ton only.
Index Number | Part Name | Quantity |
1 | Screw, Set | 2 |
2 | Cap, Shell | 1 |
3 | Shell, Unit | 1 |
4 | Pipe, Bottom | 1 |
5 | Screw Assembly, Lifting | 1 |
6a | Worm Gear | 1 |
6b |
Backlash Nut Assembly (Mfg'd and sold in sets only) |
1 |
7 | Bearing, Top Load | 1 |
8 | Bearing, Bottom Load | 1 |
9* | Screw, Set | 4 |
10* | Bushing, Worm Retainer | 2 |
12* | Thrust Race | 4 |
13* | Bearing, Needle | 2 |
14 |
Bushing, Guide (inverted models only) |
1 |
15 | Fitting, Grease | 1 |
16 | Nameplate | 1 |
17** | Retainer Ring | 2 |
18** | Bearing, Worm | 2 |
19** | Drive Lock Pin, Top Plate | 1 |
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