Messages

121

Work and Events / Re: Eames Train Brakes - Official Work Thread

« on: June 09, 2016, 09:25:23 AM »

I greatly appreciate seeing the excellent and most informative posts concerning the Eames brake system. My question about a possible precedent for a single pipe Eames continuous automatic brake system was based on my suspicion that no precedent existed, and that has been confirmed.

Mention has been made of the challenge to develop an Eames-like continuous automatic brake system that will satisfy the needs of the WW&F. I gather that considerable progress has been made.

It has been stated that the sensible approach of referring to Eames patents for design inspiration has been adopted. I think that such an approach must bring worthwhile results, if faithfully pursued. It would be of concern, however, if the WW&F were to adopt too much of the style of the Great Little Trains of Wales, great though they might be.

When planning a vacuum train brake system, one of the decisions is how to integrate the operation of the locomotive brake system with that of the trailing vehicles. Historically, commonly applied options included:
1.   Apply automatic vacuum brakes to the locomotive so that it becomes just another part of a train; or
2.   Use steam or air brakes on the locomotive that may be independently controlled when working light engine and that may be vacuum-controlled, via a vacuum/steam or vacuum/air proportional valve, from the train brake system.

For the WW&F, neither of these options is easily applicable because the locomotive brake is “straight” vacuum. Awkwardly, the need arises to provide vacuum for two separate vacuum brake systems that need vacuum creation at differing times.

The heritage value of the existing Eames Vacuum Driver Brake that is fitted to locomotive #9 is such that it should not be altered. This makes the integration of the two brake systems most difficult – or impracticable.

I have studied published photographs but I am not entirely clear as to how the various issues have been addressed in the design of the prototype continuous automatic vacuum brake. If the two systems have been kept completely separate, then there would be a need for them to be separately manipulated in service. If the two systems have been integrated, then that might spell compromise for the Eames Vacuum Driver Brake.

It would greatly clarify if we could see a schematic diagram of the prototype brake system. Then it would be clear what equipment is installed and how the various parts are interconnected. A scan of a good sketch would do.

I am not sure whether it applies throughout the WW&F but I assume that the overall aim is to preserve or recreate the state of affairs that applied on the railroad at the time of its closure, in 1933. I know that is so for locomotive #9.

122

Work and Events / Re: Eames Train Brakes - Official Work Thread

« on: June 06, 2016, 08:03:24 AM »

I would be interested to know whether any of the Maine Two-footers ever had a single pipe continuous automatic Eames vaccuum brake?

123

Two Footers outside of the US / Re: 2-footer crosses standard gauge

« on: June 02, 2016, 06:02:53 AM »

Mainlines in Queensland are laid to 42 inch track gauge.

JBS

124

Work and Events / Re: Eames Train Brakes - Official Work Thread

« on: May 31, 2016, 06:33:00 AM »

As a recently-joined member, this is my first post. I regret that some of it will be a little negative. Please understand that I greatly admire what is being achieved by the members of the WW&F Railway Museum. My intention is to contribute, from afar, in what will be an ultimately positive manner.

Safety chains have been discussed in this thread. In the absence of a continuous automatic brake system, safety chains compensate by reducing the likelihood of and controlling the risks associated with train separation in cases of coupling failure. This is necessary so that unbraked cars will not run free, putting occupants and others in danger. A further advantage of keeping the train together is that brakemen will then have the best chance of bringing all of it to rest in a safe manner.

When continuous brakes have been fitted, it may be considered that safety chains will be no longer needed. In the event of train separation, both portions of the train will be brought to rest by the automatic action of the continuous brake.

Having studied the excellent and informative posted photographs of the trial WW&F continuous vacuum brake system, I have noted that end cocks have been included in the brake pipe of each vehicle. Some of these would be accessible by passengers. Accidental or deliberate closing one of these end cocks would remove brake system continuity in a train and a safety hazard would thus be introduced: the locomotive engineer could no longer control the automatic brake system throughout the train and the hazards associated with train separation would be introduced.

Historically, automatic vaccuum brake systems have never incorporated end cocks because they are unnecessary. Hose couplings self-seal onto the mating receptacles (termed “acorns”, because of their shape) that are provided at car ends. The vacuum holds everything together. A hose can be pulled from a receptacle (at the rear of a train) and replaced to prove continuity. Inside a caboose, a Conductor’s Emergency Cock is provided and connected to the brake pipe. By manipulation of that cock a train can be brought to a stand at any time.

End cocks are unsafe, as detailed above, and they are unnecessary. One of the beauties of the vacuum brake is its simplicity. That inherent safety is compromised by the introduction of unnecessary end cocks.

Another advantage of the vacuum brake is that it permits both graduated application and release of the brakes throughout a train. That makes for smooth train handling.

I do understand that the WW&F vacuum brake system is still experimental. I am sure that the proven and exacting approach of the WW&F shop forces will eventually produce a system that will be well worthy of those magnificent trains. I am sure that all realistic standards of safety will be met.

John B Scott
Melbourne
Australia