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Worm Gear Hex Drive

www.opw-es.com

790 Series Counterbalance

PART #H30790PA 

790-SERIES-IOM-EN-01/2021

NOTE: 

Prior to any loading arm disassembly, spring tension should be 

completely relieved. Tip: To relieve tension, arm should be pushed up as 

much as possible and supported while spring tension is relieved. Spring 

coil will be loose in housing when completely relieved of tension.

Equipment: Torsion Balance Type: 790A,B,C

Balance Unit for Balancing Loading Arms

Suitable for: Loading Arm Balancing
Easy, Precise Adjustment    No special tools required

Specifications

Type: 

Right-Hand: 790A-0020 (White), 

 

790B-0030 (Yellow), 790C-0050 (Red)

 

Left-Hand: 790ALH-0025 (Black), 

 

790BLH-0035 (Gray), 790CLH-0045 (Orange)

Working Temperature Range:
 

-40°F to 176°F (-40°C to +80°C)

Installation

Spring Unit Assembly

1. Position balance unit on the bosses at back of swivel joint.
2. Fix balance unit with Bolts and Lock Washers.
3. Attach backside of Link Arm [17] to Spring Arm [15] with Pin 

[16] and 2 Retaining Rings [14].

4. Remove the 4 Socket Head Screws [18] and take Snubber 

Block [26] off.

5. Raise loading arm to highest position (as vertical as possible).

6. Attach front side of Link Arm [17] to mounting ears on loading 

arm with Pin [16] and 2 Retaining Rings [14].

7. Check balancing action by pulling down the arm. If adjustment is 

necessary, follow adjustment instructions below.

8. Install lock-down unit 788-L, if used, by following 788-L 

installation instructions.

9. Replace Cover [21] using alignment pins [1] and latches [22].

Adjustment

When to adjust torque

A. To raise loading arm higher or for more lifting action 

INCREASE

 torque.

B. To decrease loading arm vertical travel or to slow the rate at which the arm rises, 

DECREASE

 torque.

C. Note: Prior to any disassembly, Spring balance tension should be completely relieved to allow safe disassembly of level arm.

Torque

For more lifting action increase torque.
For less lifting action decrease torque.

Place ¾

"

socket wrench on worm gear hex drive.

To 

INCREASE

 torque rotate the worm gear hex drive 

counterclockwise (to the left).
To 

DECREASE

 torque rotate the worm

gear hex drive clockwise (to the right).

Easy-To-Use  

Spring Cover Latch

Summary of Contents for OPW 788 Series

Page 1: ...taining Rings 14 4 Remove the 4 Socket Head Screws 18 and take Snubber Block 26 off 5 Raise loading arm to highest position as vertical as possible 6 Attach front side of Link Arm 17 to mounting ears on loading arm with Pin 16 and 2 Retaining Rings 14 7 Check balancing action by pulling down the arm If adjustment is necessary follow adjustment instructions below 8 Install lock down unit 788 L if u...

Page 2: ...H 30320 RE Pin Torsion Spring SST Index Qty Part Description 17 1 E 20041 D1 Link Arm D1 18 4 H 31278 M Socket Head Screw ZP 31 18 X 1 19 2 H 02507 M Lockwasher CP 5 8 20 2 H 05910 M Screw Hex Cap CST ZP 5 8 11 x 13 4 21 1 E20181 790 Spring Balance Cover RH 22 2 H32321M Spring Cover Latch SouthCo 23 4 H32322M Screw Thread Forming 8 32 24 1 C 00626 M Spring Torsion C 25 1 H 30742 RS Bar Safety 26 1...

Page 3: ... lifting action increase torque For less lifting action decrease torque 1 Raise loading arm to highest position and secure 2 Hold Adjusting Nut of Spring Regulator 2 with a large wrench 3 Loosen lower Bolt of Spring Keeper and remove upper one Using a large screwdriver push Spring Keeper forward With Spring Keeper disengaged turn Spring Regulator Adjusting Nut clockwise for more or counter clockwi...

Page 4: ...pring Keeper 17 Nut 6 Spring Arm 18 Screw 7 Lever 19 Cover NOT SHOWN 8 E ring 20 Spring Compression 8 Pin 21 Snubber Retainer 10 Support Bracket 22 Snubber Plunger 11 Bearing Flange 23 E ring 12 Side Support 24 Pin DANGER Danger Before performing any maintenance always secure the Loading Arm and remove all tension from the counterbalance a torsion spring The Loading Arm counterbalance spring conta...

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