Earle Gear

Lock Bar Operators

EARLE Lock Bar Operators

Standard Models:

EG-2B     9 to 16 inch 

EG-3        16 to 28 inch

EG-4        10 – 20 inch

EG-4XL  15 TO 25 inch

Wherever heavy duty connectors are required to support shear loads between two structures yet have the ability to be withdrawn to permit the structures to move, EARLE Lock Bar Operators have proved their value time and time again. This weatherproof, self-contained operator requires minimal maintenance and provides repeatable, trouble-free service.

Standard units are available in strokes up to 28 inches and may be adapted to accommodate even longer strokes. The operators are assembled from standard parts, stocked by Steward, and are readily available for new installations as well as replacement purposes.

Linear movement is achieved through an Acme lead screw and a driven, captive nut. Both members are packed with lubricant and totally enclosed, well protected and not exposed to contamination of foreign materials in the environment.

Repeated, accurate travel is controlled by enclosed, protected limit switches that are tripped by the lock bar. The units are completely shop assembled, adjusted and tested so that field installation time is minimized. A safety interlock is provided to prevent accidental starting of the motor while the unit is being operated with the emergency hand drive.

Operator Specifications

The lock bar operator includes a motor and brake, reduction gearing and limit switches in one weatherproof, self-contained assembly.

Gearing consists of double reduction generated helical gears of heat treated alloy steel. Anti-friction bearings are used throughout. The unit is provided with a removable hand crank for manual operation and a removable protective cover for the shaft end. The reduction gears and ACME thread produce a lock bar travel speed of approximately 1.5″ per second.

A superior quality high starting torque, induction type “D” flange motor is used. This, 1675 RPM, 3 phase, 60 hertz, 208 – 240/480 volt, NEMA design D, frame B145TDZ, TENV Motor has a 15-minute duty rating and is equipped with a 3 ft.-lb. marine duty brake with manual release and safety interlock switch. It is a totally enclosed, non-ventilated, ball bearing motor designed especially for outdoor applications subject to adverse weather conditions.

Travel by the lock bar in each direction is governed by a two pole, snap-action limit switch. These provide two normally open and two normally closed contacts for each length of travel. A safety interlock switch is included, which when properly wired into the motor controller circuits, interrupts power to the lock bar motor. This prevents accidental operation of the lock bar and possible injury to personnel when the hand crank is used.

All parts of the operator are designed in accordance with ASSHTO Standard Specifications for movable Highway Bridges and AREMA Specifications for Movable Railway Bridges 1989.




  • Bascule bridge span and tail locks
  • Vertical lift bridge span locks
  • Elevator platform lock
  • Swing bridge locks
  • Gate locks

EARLE EG-2B Lock Bar Operators

The EG-2B and its predecessor the EG-2 have been in service on bridges and other applications for over 50 years.  These units are still perfect for shorter stroke and smaller envelope applications.  Current production units have the benefit of many refinements to the originals but still maintaining the original mounting dimensions and envelopes.  All EG-2B have 1.5 hp. motors with 3 ft. lb. brakes.  The units are rated for 8800 lbs. of push or pull thrust at 50% of the stall torque of the motor.

EARLE EG-3 Lock Bar Operators

The EARLE EG-3 Lock Bar Operator is intended for use in applications that will frequently be subjected to heavier loads and more rigorous duty cycles. Very wide bascule leafs, those carrying six or more lanes of traffic, as well as installations in which the guides and receivers are widely separated and 5 x 8 in., 6 x 9 in. or where even larger lock bars are required, are typical examples for use of EG-3 units.

Additional strength and rugged support for the reaction forces, caused by the passage of vehicular traffic, has been built into the forward guide that is incorporated into the steel casting which encloses the lock bar stem/lock bar pin connection and adjustable limit switches. A wide, high strength bronze guide bushing located in the bar guide cover ensures more than adequate capacity for support of the live loads. The installed EG-3 operator is a stiffer and more rugged assembly because of the greater number of larger diameter mounting bolts located in the vicinity of its forward guide. This operator can be supplied for strokes up to 28 inches.

Generally the drive motor specifications are similar to the motors used for EG-2B operators. We can also furnish 3 or 5 HP motors on EG-3 units.

Like the EG-2B, the EG-3 can be mounted in any position, including upside down. The gear housing can be rotated 90 for reduced height installations.

EARLE EG-4 and EG-4XL Lock Bar Operators

The Earle EG-4 and EG-4XL are trunnion-mounted linear actuators utilizing the same rugged system as the other EG operators.  The 1-7/8 inch diameter (2-1/4 in diameter on the XL) is driven by the same 2 inch diameter acme screw drive system used on the EG-2B and EG-3.  The EG-4XL has a larger diameter bar for longer strokes.  The rod and threaded stem are machined from one piece of high strength steel bar stock. Two pole, snap action, lever type limit switches acting on the rod inside the stem guide housing are provided to control the stroke of the rod.  The housings and rods are built to order so strokes from 15 inches to 25 inches can be accommodated easily.  Shorter strokes are accomodated by simply adjusting the limit switches.  The stem housing is fabricated steel incorporating a bronze rod guide and fully machined 1-1/2 inch diameter trunnions.  The rod guide is lubricated using a provided button-head fitting.  The standard rod end is 1-1/2 inch diameter male thread.  However, spherical rod ends, clevis connections, or other options are available.  The EG-4 and EG-4XL, like all EG operators, can be mounted in any position, including upside down.  In addition, the drive assembly can be mounted 180 degrees from the position shown.  Steward can also design and fabricate special trunnion supports with spherical bearings, as shown in the photo above.

For service as span locks on bridges, the EG-4 and EG-4XL are compatible with Earle Cushionloks guides and receivers. An additional rear guide is used to control the bar completely isolate the operator from the reactions of lock bar.

The EG-4 and EG-4XL are available in three thrust capacities.  The thrust rating is the same for push and pull.