Cass Street Bridge Rehabilitation Specifications.docx

Motor and Machinery Brakes

1. General

1.1 Description

1.1.1 This section includes requirements for furnishing two electro-hydraulic motor brakes and two electro-hydraulic machinery brakes per bascule leaf (8 brakes total). The brakes act upon brake wheels press fit onto shafts as called out on the typical mechanical drawings.

1.1.2 Each brake must be a new Association of Iron and Steel Engineers (AISE) mill duty drum brake operated by sealed electro-hydraulic thrusters with integral hydraulic delay adjustable from 0 to at least 5 seconds to provide smooth, staggered application of all brakes. Adjustment must be infinitely adjustable between the minimum and maximum settings. These adjustments must be allowable with the brake in full service. Set the down-stroke time delays of the thrustors in such a manner that the brakes are not applied simultaneously should electric power fail while the span is in motion. Adjust the intervals between the setting of the brakes to obtain smooth stopping of the span in the shortest possible time. Only an internal time delay valve constructed of stainless steel is acceptable.

1.1.3 The brake wheels will be procured separately.

1.1.4 Electro-hydraulic thrustors and brakes must be capable of operating while rotating at least 80 degrees without a change on brake set torque of more than 20%.

1.1.5 Provide the oil used in the thrustor operating chambers of the brakes to be of a grade as recommended by the manufacturer and approved by the Engineer. It will have a free operating temperature range between -40 degrees and 66 degrees Celsius. Throughout this temperature range there must not be any material change of operating characteristics.

1.1.6 All new thruster brakes must be equipped with an external braking torque adjustment spring with gauge showing the brake torque setting that must be easily visible and accessible for adjustment once the brakes are installed. Install spring-set, thrustor-released, shoe-type, open brakes with corrosion-resisting fittings. Brake will have the drum size and torque requirements as listed on the plans, with permanent torque setting limited as required.

1.1.7 All thruster components including bearings, seals and gaskets must be UL listed.

1.1.8 Each brake must be provided with a hand release and hand release lever type limit switch for interlocking purposes. The hand releases will not change the torque setting or require removable levers or wrenches. It must not be possible to set the hand release of the brakes without tripping these switches. Hand release mechanisms will be provided on the side of the brake away from the main reducer. (Right-hand and left-hand units are required.) Switches will be roller plunger types or heavy-duty rotary lever arm. Lever arm roller will be 1.5-inch diameter, with 3.75” inches of adjustment. Switch shall be NEMA 6P+ rated with epoxy potted cord sets.

1.1.9 In addition to the hand release limit switch, mount two lever type limit switches on each brake. Ensure one indicates that the brake is fully set, the other that the brake is fully released. Assure that the brake released limit switch (which will have two normally open contacts) trips when the brake is electrically released or hand released. Ensure the brake set limit switch has one normally open and one normally closed contact and is tripped when the brake is fully set. Ensure switches are heavy-duty rotary lever arm. Lever arm roller will be 1.5-inch diameter, with 3.75” inches of adjustment. Switch shall be NEMA 6P+ rated with epoxy potted cord sets.

1.1.10 Thrustors will actuate by 480-volt, three-phase, 60 Hertz, totally enclosed, squirrel cage motors controlled by magnetic contactors with manual-reset thermal overload relays. The rated stalled thrust of each thrustor shall not be less than 135 percent of the thrust actually required to release the brake with the torque adjusted to the continuous rated value.

1.1.11 Ensure each brake is provided with automatic wear compensator.

1.1.12 Equip each brake with a NEMA 3R enclosure, which encloses the entire brake assembly, including the brake thrustor unit, and the brake wheel, and should not prevent brake hand release operation.

2. Rolling Element Bearings

2.1 Size anti-friction bearings for a B-10 life of 40,000 hours as defined by ABMA for the ratings shown in the table below.

2.2 Provide pillow block bearings, adapter mounted, self-aligning expansion and non-expansion types, as called for on the plans. Provide cast steel housings capable of withstanding the design radial load in any direction, including uplift. Bases shall have the feasibility for a four-bolt connection. Sub-drilling and final reaming of mounting holes from the solid shall be completed with supporting steel work. Provide seals that retain the lubricant and exclude water and debris. Provide high-strength steel cap bolts for pillow blocks. Use cap and cap bolts capable of resisting the rated bearing load as an uplift force.

Bearings

Brakes

Custom frame dimensions to match existing. Motor mount to be reused.

Brake Wheels Details (For Information Only)

“5” (in.)

Bore Dia.

(in.)

(in. x in.)