USRA Designs

USRA Mikado Steam Engine

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Appliances - Brakes

 

Air Components

Westinghouse introduced the No. 5-ET brake in 1905, replacing the old straight air locomotive brake valve and a triple valve with a redesigned locomotive Independent Brake Valve and Distributing Valve. The No 6-ET brake system of 1906 was a redesign of the 5-ET, with no new functional changes, but with improved performance and more easily serviced components. The 6-ET quickly became accepted as the de facto standard locomotive brake for the next 51 years!

The USRA specified that Westinghouse Air Brake Co. or New York Air Brake Co. systems were to be used. Below are the USRA specifications for the USRA Mikados that were built by Baldwin.

 

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Steam Locomtive Air Brakes Steam Locomtive Air Brakes

 

The major components of the system included:

No. ET-6 8-1/2" Cross Compound Air Compressor (200 lbs steam pressure against 140 lbs. air pressure)

SF-5 Compressor Governor Double Sight feed Air Cylinder lubricator (self closing type)

B-6 Double Pressure feed valve with f pipe bracket

H-6 automatic brake valve with collapsible equalizing piston

10" x 14-1/2" Equalizing Reservoir

S-6 Independent Brake valve 5" duplex air gage (main reservoir and equalizing reservoir)

No. 6 Distributing valve with E-6 Safety valve, double chamber reservoir and plain cylinder cap

(2) 14"x 12" type B driver brake cylinder, with side flanges out to 7-5/8" from center line with jm type expander

(3) 20 1/2" x 72" enamelled main reservoirs, standard tapping

The following pages provide a brief description of these components.

 

(click on picture for a larger view)

Steam Locomtive Air Brakes Steam Locomtive Air Brakes Steam Locomtive Air Brakes

 

 

(click on picture for a larger view)

Steam Locomtive Air Brakes Steam Locomtive Air Brakes Steam Locomtive Air Brakes Steam Locomtive Air Brakes

Westinghouse 8 1/2" Cross Compound Air Compressor

Source: 1922 Locomotive Cyclopedia of American Practice

Westinghouse 8 1/2" Cross Compound Air Compressor

Source: Westinghouse Air Brake system, 1911

Westinghouse 8 1/2" Cross Compound Air Compressor

Source: 1922 Locomotive Cyclopedia of American Practice

Westinghouse Duplex Pump Governor

Source: Westinghouse Air Brake system, 1911

 

Based on the few fireman side photos of Rutland's mikados late in their careers the, output from the compressor was routed to the three reserve tanks located along the boiler in series. This differs from the information for the first USRA light Mikado, the B&O 4500, which had the front fireman side and engineer side tanks piped in series and the rear fireman side tank connected through a tee behind the tank on the engineer side. A pipe ran over the boiler connecting this tee to the the rear fireman side tank.

 

(click on picture for a larger view)

Steam Locomtive Air Brakes Steam Locomtive Air Brakes

Piping arrangement for the Westinghouse 8 1/2" Cross Compound Air Compressor

Source: 1922 Locomotive Cyclopedia of American Practice

Westinghouse No. 6 ET brake piping

 

Source: Wikipedia

 

Foundation Rigging

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USRA Mikado Brake Rigging

Based on USRA drawings for the component parts (i.e., beams, links, equalizers & rods), but I had to figure out how the pieces fit together for the whole rigging.  Let me know if you see anything incorrect.

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