REDUCERS

In 1986, Steward Machine Co. bought the assets of Earle® Gear and Machine Co., Philadelphia, Pennsylvania. The same reliable Earle® Gear Speed Reducers and Lock Bar Operators are now being manufactured by Steward Machine Co. in Birmingham, Alabama, utilizing Earle® concepts and engineering data.

Earle® Speed Reducers are specially designed and manufactured to meet the demands of low-speed, high-torque applications. They have been used successfully for more than 90 years to operate movable bridges, in heavy lifting and hoisting machinery, and other custom drives. In addition to conforming to appropriate American Gear Manufacturers Associate standards, Earle® units also incorporate the benefits gained by such long experience. They have been designed with reserve strength and dependability to safely control massive inertial loads.

Earle® pioneered the development and use of Differential Speed Reducers in movable bridge operating machinery systems, and Earle® reducers continue to occupy a position of leadership in that field. The differential reducer incorporated a balanced, three-pinion, bevel gear assembly which ensures load sharing between the two output shafts.

Earle® Speed Reducers are compact, self-contained, fully enclosed units of high mechanical efficiency. Quiet in operation, they provide for automatic lubrication of gears and bearings. The large variety of sizes and capacities available is listed and illustrated on the following pages. In addition, we specialize in designing and manufacturing custom gear reducers and mechanical drives for unusual applications.

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CUSHIONLOK®

The Cushionloks® system consists of a rectangular bar that fits through a guide on one leaf tip and into a receiver on the other. This allows shear load transfer from one leaf to the other, so the leaf tips deflect uniformly during the passage of vehicular traffic.

Stiff disc springs support the wear shoes in the guide and receiver housings and ensure firm, continuous contact between the bar and shoes. Shock loads to the bar are reduced, zero clearance exists between the bar and shoes, and uncontrolled bounce of the leaf tips is eliminated.

The first Cushionloks® were installed and put into operation in February 1995 on the Bellaire Causeway Bascule Bridge, Pinellas County, Florida. Since then, many have been installed on bridges with varying sizes and traffic loading. Lock bar sizes range from 4 x 6 inches to 7 x 10 inches for shear load transfers from 25,000 lbs to 120,000 lbs. per lock bar. In all installations, the maintenance savings have been significant because bar and shoe wear has been reduced and emergency maintenance has been minimal. The leaf tips continue to deflect uniformly and without pounding or noise during the passage of heavy traffic.

Several improvements have been incorporated into the current production of the Cushionloks® guide. The most significant is the addition of screw adjustable spring settings.   Now all preload is set by simply tightening a threaded cartridge.  This way, preload can be added or subtracted anytime without removing the lock bar or shoes or dissembling the spring stacks.

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LOCK BAR OPERATORS

Standard Models:

  • EG-2B9 to 14 inch
  • EG-316 to 26 inch
  • EG-4XL15 and 20 inch

Wherever heavy-duty connectors are required to support shear loads between two structures yet can 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 per ASSHTO Standard Specifications for Movable Highway Bridges and AREMA Specifications for Movable Railway Bridges 1989.

Uses

  • 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 maintain 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 leaves, 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, have 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 poles, snap action, and 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 accommodated 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 to completely isolate the operator from the reactions of the lock bar.

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

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PILLOW BLOCKS

Benefits:

  • Steel housings
  • Two-piece, split construction
  • ASTM B-22 bronze bearing
  • AASHTO and AREMA load ratings
  • Two-way thrust capacity
  • Sub-drilled or blank mounting holes
  • Brass, laminated liners
  • Double spiral lubrication grooves
  • Giant button-head lube fitting
  • 1/2 inch nominal, full size, stainless steel shim packs

Specifications

Housings:

Housings are ASTM A38 plate steel. Two-piece split construction with accurate cap and base registration. Caps are secured by threaded studs with double hex nuts. The cap is equipped with a button head lubrication fitting threaded directly into bushing. Base bolt holes are blank to permit field drilling and reaming (AASHTO 6.7.7.1.1).

Bushings:

Double flanged, split-type bronze bushings conforming to ASTM B22 UNS ALLOY C91100. Counter sunk flange screws are used to secure the bushings in the housing and prevent rotation. Bushing bores have ¼” wide x ⅛” deep double spiral grooves for grease distribution (AASHTO 6.7.7.1.2)

Liners:

Each pillow block is furnished with ¼” thick brass liners consisting of one solid piece of 0.125” thick and one piece 0.126” thick in 0.003” laminations (AASHTO 6.7.7.1.3).

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