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Union Pacific Unveils A New 3000 HP
Diesel Electric Rotary Snow Plow

This page was last updated on February 5, 2014.

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By Harold Rees, 1966

Since the late 1880s the steam powered rotary snow plows have been one of the most spectacular pieces of railroad maintenance equipment. During mild winters they are seldom used -- but when winters are severe they are a "must". Blizzards are a rotary's best friend -- testing them in a manner which cannot be simulated on the test stand -- revealing any shortcomings in a glaring manner.

The severe blizzards which occurred in the 1880s were responsible for the development of the rotary snow plow. Wedge plows could handle ordinary snow fairly well but were unable to handle snow that was drifted deep and hard by western blizzards.

The first successful rotary snow plow was purchased by the Union Pacific in 1887 after it had successfully demonstrated its capability between Granger, Wyoming and Huntington, Oregon. This successful rotary plow was based on a patent granted Inventor Orange Jull and assigned to John S. and Edward Leslie. It was constructed for the Leslie Brothers by the Cooke-Locomotive and Machine Works at Paterson, New Jersey. This first rotary was so successful that three more were immediately ordered by the Union Pacific for delivery before the next winter. The next three rotary plows built by Cooke Locomotive·and Machine Works for the Leslie Brothers were delivered to the Union Pacific by December 1887. Other railroads followed suite and by 1903 a total of 64 rotaries had been sold by Leslie Brothers to various railroads, located mostly in the West. All of these were constructed by Cooke Locomotive and Machine Works. A total of five had been purchased by the Union Pacific.

From 1905 to 1937 the so-called Leslie Rotaries were built by American Locomotive Company. A total of 71 were constructed, of which seven were purchased by the Union Pacific.

The Leslie rotary snow plow consisted essentially of a conventional steam locomotive boiler mounted on an underframe supported by two 4-wheel trucks. Attached to the front end of the underframe was a rotary wheel enclosed in a wheel housing. The rotary wheel was driven by an ingenious mechanical arrangement which combined the conventional steam locomotive cylinders, pistons, main rods and main drivers with a gear box attached to the rotary wheel shaft. The plow engtneer's cab was located directly behind the rotary wheel housing and ahead of the smoke stack. Originally the plow engineer's "controls" consisted of a whistle and emergency brake valve. The throttle and reverse lever for the rotary were located along side the fire box and were operated by another enginernan. The pusher locomotive was operated by still another engineman. Both plow and pusher enginemen tried to operate in response to whistle signals from the man in the forward cab. Poor communication made operation very difficult -- if the plow was pushed into the snow faster than the rotary wheel could "digest" the snow and cast it out, then the wheel would stick and it would be necessary to thaw it out with steam from the boiler. This thawing operation was laborious and time consuming.

During the years 1887 to 1922 the Union Pacific and connecting lines, which later became part of the Union Pacific system, acquired a total of 17 rotary plows constructed along the above lines.

Through the years the basic design did not change -- it was eminently successful. Since they were only used when winters were severe, their total operational time was short, hence they were exceptionally long lived.

Of the first five rotaries built in 1887 and 1888 for the Union Pacific or its later acquired connecting lines, none were officially retired until 1958. In that year two were retired and two were stored unassigned. One is still Stationed at Rawlins. Incidentally, the one stationed at Rawlins is the first rotary constructed at the Cooke Works. It is seldom used because rotaries built at a much later date are stationed at Green River and Cheyenne and are used in preference. But it still serves as standby protection -- just in case it is needed -- 80 years after it was constructed.

The blizzard which occurred in January 1949 focused attention on the railroad's snow fighting equipment. For many years the winters had been mild, and rotaries were not required. Some had been lulled into under estimating their importance. The sudden onslaught of the '49 blizzard gave the rotaries a chance to prove their worth, and also pointed out the need for both replacement and additional equipment. Two steam driven plows were immediately ordered constructed by Lima-Hamilton Corporation. These differed from previous plows in that the rotary wheel was mounted on roller bearings and was driven by two 3-cylinder Shay steam engines. These two steam plows are considered the most powerful steam rotaries in the world, developing approximately 2000 HP at maximum wheel speed of 150 RPM.

With the passing of the steam locomotive, and the gradual replacement with diesel-electric and gas turbine-electric motive power, the fuel and water facilities used with steam power are also eliminated. With no fuel and water facilities the steam driven rotary snow plow is in somewhat the same situation as the dinosaur was when his environment changed. Rotary snow plows have to use the same facilities as the railroad's motive power.

Immediately followlng the historic 1949 blizzard engineering studies were started to develop a diesel electric rotary snow plow. The design concepts of this rotary plow were to utilize as much as possible the components in use on diesel electric units, and to have at least as much power as the large steam driven rotaries constructed in 1949.·It was also desired to make the plow self-controlled so that the plow engineer would have full control of both the rotary plow wheel and the diesel electric pusher units. This would simplify operation and eliminate the problem of coordinating the operations of plow and pusher engineers.

As the result of these studies, a new design rotary snow plow, road number 900080, was constructed in the railroad's shops at Omaha during 1958. Stationary load testing was completed during November, and the plow moved to Pocatello, Idaho for road testing. On March 3, 1959, the plow made its initial road plowing trip, opening up the 56 mile line of branch track between Ashton, Idaho and West Yellowstone, Montana in twelve hours. This branch line is not operated during the winter months. Removal of the snow which accumulates during the winter months is a major operation. This winter the snow varied from 2 to 8 ft. in depth, with a water content of approximately 27 percent. Forward speed of the plow during this operation varied from 2 to 14 mph. A single GP-9 pusher unit was used throughout the 56 mile run, except for seven miles of one to two per cent grade through Reas Pass, where it was necessary to cut in a second GP-9 pusher unit. During the trip the rotary plow engine operated in maximum throttle position for five hours 39 minutes. Total time for main track plowing was 8 hours 12 minutes. The remainder of the time was consumed in digging out switches, plowing sidings and wyes, reversing rotary wheel to cast on opposite side of track, etc. There was no mechanical or electrical trouble. The plow operated with much less vibration and noise than a steam powered plow. The speed of this operation was phenomenal -- had the steam driven Lima-Hamilton built rotary been used it would have required 32 to 40 hours of plowing.

Diesel-electric rotary 900080 has been used five times to open up the Yellowstone Branch after a winter's accumulation of snow. This branch has proven to be an excellent proving ground. Had it not been for this branch, any testing would have been impossible because of the succession of mild winters.

The tremendous development which has taken place in freight oar design has reflected on snow fighting equipment. Longer and wider cars require a wider cut on curves to provide clearance at the mid point of the car. Since rotary wheel housings were already close to the maximum·clearance, it was not possible to make the wheel housing wider. To obtain a wider cut on curves the plow housing of the 900080 was equipped with hydraulically actuated wings which increase the width of out from 12'6" to 14'0".

The successful operation of the 900080 and the wealth of test data accumulated from 1958 to 1965 dictated that a second diesel electric plow be built. The second plow was to be essentially the same as the 900080, except larger and more powerful. Wheel diameter to be increased from 11'2-1/2" to 12'-0" and diesel engine power raised from 1800 to 2500 HP.

The second rotary, road number 900081, designed and constructed by the Union Pacific, was completed and stationary tested at Omaha in November of 1966. Its design and construction incorporated many special features. In order to reduce weight as much as possible, maximum use was made of high strength alloy steels. Special welding techniques were used for these materials and every weld supervised and inspected. Only in our own railroad shop could such insistence on welding perfection be maintained. It would not have been feasible in the average contract shop.

The equipment used in the 900081 is impressive. A 3000 gross HP 16 cylinder diesel·engine drives a generator which supplies power for the four motors which drive the 12'-0" plow wheel. An inertial type air cleaner pressurizing the car body, supplies 40,500 cubic feet of clean air per minute to supply air for engine combustion, generator cooling and motor cooling and prevents the entrance of snow to the car body. A steam generator can supply 1600 lbs. of 250 psi steam per hour if required to thaw out the rotary wheel if it should become stuck. The diesel engine fuel tank carries 2150 gallons. ·The water tank supplying the steam generator carries 1765 gallons. 550 gallons of additional diesel fuel are carried for the steam generator. Seven blowers are required to furnish cooling air for the motors and gearing driving the rotary wheel.

During March of 1966 a blizzard hit the Dakotas. 97,000 head of livestock perished. Railroads in that area had to rely on rotaries to open up the lines. Once again a blizzard had underscored the need for rotary snow plows.