Air Brake Retainer Valve c1900

The article below was scanned, then assembled from one volume of the Science of Railways series. The binding is stiff and brittle so it was not possible to force the pages perfectly flat on the scanner.

Retaining Valves in General: 

Engineers operating on lines with flat or average grades ... would want a normal release of the car brakes as they continued to run a train along the track. Releasing the brakes happened through the same process as that used to refill the cars' air reservoirs so the reservoirs would be ready for the next brake application. Normally, releasing and recharging brakes at the same time did not create a safety problem.

However, engineers descending very steep grades would need the ability to refill the cars' individual brake systems WITHOUT the train running away down the grade. The retainer valve on each car was designed to be 'turned up' before trains descended steep grades. While engineers could recharge their brake system at the 'normal' rate, the train brakes would release at a special 'slow' rate because of the retaining valve adjustment made to all of the cars before descending the grade. After the bottom of the grade was reached, the retainers were turned 'down' - back to their normal setting.

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With the original retaining valve:

With the handle in the 'six o'clock' position, air exhausts from the car brake cylinders without impediment to atmosphere.

When the retainer handle is turned up to the 'three o'clock' position as it is seen on the diagram, the car brake cylinder exhaust must lift a weight off its needle valve seat, then the exhaust must thread its way through the small exhaust port marked 'd'. 

... On the CPR's Big Hill, trainmen working a passenger train downhill were instructed to ensure this aperture was clear using a 1/16 inch wire.

from: The Science of Railways; 1891-1900; The World Railway Publishing Co.

... The Westinghouse High and Low Pressure Retaining Valve used the same handle positions for the same effect as the first retainer illustrated ...

However, for the circumstances when EXTRA car brake cylinder pressure was to be retained as the engineer recharged the brake system while in motion, an INTERMEDIATE handle position between 'turned down' and 'turned up' was created. This intermediate position was 'stronger' than the normal 'turned up' setting. The High Pressure setting forced the exhausting brake cylinder air to lift an ADDITIONAL weight.

As train air brake experience was gained, and as motive power and car weights increased, it was determined that this new setting was necessary to maintain control of heavy trains on steep grades.

CPR 1909 Brakes on the Big Hill, Part 1 - Passenger Trains

(Four Big Hill technology posts are listed together under Railway Technology)

Somewhere I purchased a rough, coffee-stained, stapled photocopy of a 1909 CPR employee timetable which covers the track over the 'Great Divide' in the Rocky Mountains. No source is indicated. 

In its own way, the timetable marks a divide between the elite 'mountain crews' who ran CPR trains on The Big Hill with its exceptional 4.5% grade ... and normal 'run-through' crews operating over the grade reduction achieved through the construction of Spiral Tunnels which cut this gradient approximately in half.

In fact, the Spiral Tunnels opened three months after this timetable became effective. So the procedures outlined represent the final refinement of the CPR's methods and technologies for getting trains safely between Stephen and Field on that exceptional mainline grade.

Although it happens rarely - freight runaways still occur on this section of track, even with computer and dynamic-braking equipped diesel-electrics. In relative terms this remains the 'Big Hill'.

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To understand the era, I tried to find some illustrations of the technology used during this period. The following two images are Master Car Builder diagrams for passenger cars which were reproduced in 'The Science of Railways'. 

from: The Science of Railways; 1891-1900; The World Railway Publishing Co.

from: The Science of Railways; 1891-1900; The World Railway Publishing Co.

An excellent article based on notes made by Thomas Huntley Crump regarding the early practices in the region appeared in the Canadian Railroad Historical Association's Canadian Rail of December 1974 - this can be read on line. As always happens, there were sometimes modifications to the practices prescribed in writing - which follow below.

While the hardware pictured above looks labour-intensive to build, and quaint in its details and workmanship, this was also a time of significant innovation. Crump states that 'Miller bars' ran through the mountains in the early days rather than the Janney coupler. Automatic train air brakes had just been developed by Westinghouse when the CPR main line through the mountains opened. Although Janney couplers and automatic air brakes made the running trades safer, the crews were working with new technology on a new railway line. 

There were other technologies to master on the hill such as engine 'water brakes', and an electric staff system to regulate track occupancy on the hill - both covered in Part 2. Management was probably still developing its ideas about how things should be run to get the required balance between speed and safety.

Things were 'simple' for the workers: there was one single top priority: safety. The other single top priority was running on schedule.

Certainly, the mountain crews would become expert in the practice of their unusual craft ... and something was probably lost when 'just anybody' could run a train between Laggan and Field.

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This first post will look at the strict rules for handling passenger trains. Perhaps no one would miss a few boxcars in the bush, but prominent people travelled on these main line passenger trains. A lot of CPR heads would roll if this section of Canada's only modern land link between Atlantic and Pacific killed important passengers on a regular basis.

Here is the timetable showing the scheduled trains. I have altered the original printing slightly to include the westbounds and eastbounds in one image and to rotate the footnotes 90 degrees so you can read them easily.

The Big Hill section includes the point of the continental divide at Stephen in the east and Field to the west. Below I have skewed a Government of Canada topographic map with 1980 data to conveniently outline the physical features.

Between Hector and the rectangle L551 was the steepest part of the grade. On this map, the old Big Hill route is occupied by the highway in places.

If you consider all the trouble and money taken to loop the track through the Spiral Tunnels, you can imagine that an almost straight line from Hector to L551 would have been unusually steep.

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from: Van Horne's Road; Omer Lavallee; 1971-1981; Railfare Enterprieses Ltd

The grade required 'safety switches' which were permanently attended by switchmen. These three switches were 'normal' when lined for the steeply-ascending, dead-end diverging route. As you will read, only a whistle signal from the descending engineer, and the switchman agreeing with the engineer's assessment that the train was under control, would result in the switch being lined so the train could continue down the main track. Safety Switch No 1 is shown below.

To make a long rule short:

Rule 2 states that brakes must be operating normally on each passenger car. Otherwise that car must be braked by hand within the train so that 100% of the brakes are working in some fashion during the descent.

A Science of Railways article on retaining valves circa 1900 is here: Air Brake Retainer Valve c1900

Rule 4 forbids any movement following a passenger train between Hector and Field ... so that a passenger train will not be struck if the movement behind it loses control on the hill. This meant that for the full 45-60 minutes that it took a westbound passenger train to descend 15.6 miles, it would be the only traffic allowed on the hill. Perhaps this helps explain the often-repeated story that dining cars were not put on the first CPR trains through the Rockies to maximize the number of passengers which could be carried on a train.

Rule 8 is interesting as it directs trainmen to change a burst air hose without turning the cut-off cock to avoid the risk of train line pressure rising and train brakes being released inadvertently.

Rule 13 affects the 'normalling' of the retainer valves on cars usually used in passenger service on the approach to Field. However, freight cars on the headend (probably with roof-mounted retainers) are exempt until the train stops at Field.

Rule 14 wants the tailend of the passenger train which has just arrived at Field protected at once by having a crew member turn the switch behind it ... and Rule 4 wants Hector to be notified immediately of the arrival so more traffic can be released to descend the hill.

This unmailed postcard is undated, and hand-painted in Britain but may be circa 1900 or before.

Below I have enlarged the lead power. Shays were reportedly used on the Hill at first, but proved to be too slow. The lead has some Shay-ish qualities. It seems to be putting out more exhaust than the other two.

This undated postcard, printed in Victoria BC, was not mailed. Seen beyond the tunnel is the location where the serious grade began. Notice that the relatively light rails are spiked without tie plates. The shack to the right of the tunnel may be for maintenance of way supplies, or it may shelter a rock watchman.

from: Canadian Rail; December 1974; CRHA. Photo from 1898 by MM Stephens, agent at Field. Switchman is Pete Thibodeau.

Safety Switch No 1 is shown again. The switchman is attending his switch and the steepness of the runaway track is seen. Notice the stub switch. Wires from the telegraph system lead to the substantial switchtender's cabin. The magazine caption states the locomotive is ascending, but the dust or smoke might actually be trailing it down hill. Once the photo has been taken the switch will be lined for the runaway track. 

Avid railway photographers are pulling their hair out because a 3/4 view of a locomotive is obscured by a pole. If only they could have done another runpast! 

from: Canadian Rail; December 1974; CRHA.

Once again, to try to imagine the 'human experience' of railroading on the Big Hill, here is a photo of the technology in use circa 1905 with the Kicking Horse River rushing toward the Pacific below. Two of the 562's crew seem relatively relaxed as they look down their train. The 562 has a respectable main air brake reservoir beneath the cab. The truss rods of the wooden equipment are seen. 

Indeed, it is thrilling to be pushed up a hill by a steam locomotive working hard. The sights, sounds and smells of a train fighting its way up the Big Hill would have been unforgettable. However, all we have seen are passenger trains ascending the hill ... and a single light engine.

... But so much energy was put into the legalistic language, to create airtight boxes of logic, to regulate the descent of passenger trains. 

In a relative way, tourists would probably have been rather bored by the hour taken up with both the preparatory fiddling around, and then the squealing metal-on-metal descent from Hector to Field. Most of the trip was made at a the speed of a person jogging beside the tracks ... or slower.

But for those who really understood how gravity affects tons of steel and wood which could run away in some kind of hell-bent acceleration at an exponential rate ... the thrill of the hill would have been in how a runaway was being prevented during every minute of the descent. 

Except for the ratcheting of the occasional hand brake, it was all being accomplished with fluids: air, some very hot water and steam. In turn, and when required, the conductor, trainmen and fireman would play their parts. For the most part, disaster was being staved off through the controls manipulated by the engineer. 

Ultimately, the passengers and the crew might owe their lives to the railway employee seeming to do the least ... someone who was seen just throwing a switch and waving to the engine crew as they passed.