Monday, March 2, 2009

Lewiston Hill and Dynamic Brakes!

Northern Pacific 555, Auburn Washington, May 27, 1961. As regular readers of my blog have noted, Auburn was a favored spot to shoot locomotives. The diesel shop was right next to a rural road, and there were no fences, under-fed dogs or snarling railroad agents. And there were always plenty of units to photograph.

Northern Pacific took delivery of quite a few Geeps without dynamic brakes. Somehow, missing the blister housing for the resistor grids gave the unit an “unfinished” look. But since NP 555 was assigned to the Tacoma subdivision for most of her life, with no grades to speak of, there was no need for dynamic braking.

So. Lewiston Hill and Dynamic Brakes. Well, let's see if I can stitch this together coherently.

There are several ways to control a vehicle on a downgrade. The most obvious control is brakes. But on long descents, brake shoes can heat up and fail. One highly successful method of providing additional braking capability for a truck turns the diesel engine into an air compressor – creating the raspy racket that prompts town councils to post “Compression Brakes Prohibited,” or “Jake Brakes Prohibited” at the city limits. Remarkably, Jacobs Vehicle Systems is fighting back against “Jake” signs, as “Jake Brake” is a registered trademark!

One of the more severe grades in the Northwest is the Lewiston Hill. Here US 95 drops dramatically down from the Palouse Country to the Snake River. 3 miles of 6% grade followed by 4 miles of 7% grade! There are five runaway truck escape ramps. When I was there working on a documentary video program, there was an average of one runaway truck per week.

As you can see, two fellows really had a pucker trip onto Ramp #3, one at close to 100 miles per hour and ran off the end of the ramp! The Idaho Port of Entry building, situated between the north and south bound lanes of US 95 had a virtual mountain of those big blue barrels containing sand, protecting the up hill face of the building!

I spent several hours hanging out of Bell helicopter, with my door removed, video taping trucks descending the Lewiston Hill, for a program promoting the “Hale Hydraulic Retarder.” But I’m drifting off course here …

As the Jacobs Brake turns the prime mover on a truck into an air compressor to create resistance, the dynamic brake on a locomotive allows the engineer to turn the traction motors into generators, creating electrical resistance to slow the locomotive.

That resistance manifests itself in a bank of iron grids, similar to the heating grids in your kitchen toaster. These grids are mounted atop the engine compartment, and were easy to spot on Geeps and Special Duty locomotives, due to the “blister” containing heat dissipating fans, to keep the iron grids from melting!

Northern Pacific 555 was caught up in the “Great Merger” of 1970, suffered the dreadful “Cascade Green” treatment and renumbered Burlington Northern 1629. She was retired in October 1982 and sent to Joseph Simon & Son’s down on the Puyallup River in Tacoma, to be converted into razor blades.

Fate smiled kindly on BN 1629, nee NP 555, and she was sold by Joseph Simon & Son’s to become 110 on the Pend Oreille Valley Railroad in 1984. She finally ran out of track in 1993, after 41 years and god only knows how many miles.

Railroad Stuff: Northern Pacific Railway 555, built by Electro Motive Division as a GP-7, 1,500 hp, in March, 1952, serial number 15687.

3 Comments - Click here:

SDP45 said...

I believe only 1 NP GP7 survives to this day, now working on the Rarus Railway in Montana.
A few of the NP GP7s had dynamics, which was very uncommon on the "Hill" roads. No GN or CB&Q GP7s had dynamics.


Bill ~ {The Old Fart} said...

Our Transit Buses we drive have Engine Retarders that help slow the vehicle down as well works with the transmission, like gearing down. It Saves on the brakes and the compressor constantly having to recharge the tanks. Of course on icy snowy roads I turn the Retarder off, keeps the back end of the bus from suddenly fishtailing. Thanks for the read, I enjoyed this.

Robert in Port Townsend said...

Yes, there are several types of retarding systems, that I didn't want to get into! When I was in Lewiston shooting, my client was Hale Hydraulic Retarder of Portland, Oregon. Invented by the Hale Brothers down in Three Rivers, Oregon, when engaged, the diesel prime mover became a hydraulic oil pump! Oil flow was controlled by a lever in the cab, giving infinite speed control. I rode up and down Lewiston Hill several times in a Kenworth grain hauler so equipped. He was able to hold the load, a grain trailer, for seven miles at constant 26 miles per hour - using 4th direct and the Hale Hydraulic Pump!

Post a Comment

"Comment" is for sharing information related to this article. "Anonymous" comments are not published.