Budd RDC technical stuff

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Just-Thinking-51

Just-Thinking-51

Very bored and cranky pundit
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Budd RDC were problematic fresh out the factory. Completely amazing people are still trying to use them.

The problem or weakness was the transmission. Think an automobile standard transmission but harder to operate. If you missed a gear you would have to complete stop it to put it back in gear and start rolling again. Downshift for hills require, upshifting required for higher speeds. A lot of work. Unlike a truck when you can recover and float into gear. You match the rpm to the trucks speed to your gear input. A Budd RDC twin engine and twin transmission with or without additional RDC could not recover and had to stop to get it back in gear.

Surprised someone who truly wants to use these railcars, just has not gone to a traction motors with generators set up.

It was a bad design choice by Budd. So much potential but hard to operate, and high maintenance cost.
 
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Just-Thinking-51 said:
Budd RDC were problematic fresh out the factory. Completely amazing people are still trying to use them.

The problem or weakness was the transmission. Think an automobile standard transmission but harder to operate. If you missed a gear you would have to complete stop it to put it back in gear and start rolling again. Downshift for hills require, upshifting required for higher speeds. A lot of work. Unlike a truck when you can recover and float into gear. You match the rpm to the trucks speed to your gear input. A Budd RDC twin engine and twin transmission with or without additional RDC could not recover and had to stop to get it back in gear.

Surprised someone who truly wants to use these railcars, just has not gone to a traction motors with generators set up.

It was a bad design choice by Budd. So much potential but hard to operate, and high maintenance cost.
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Are you saying that the engineer had to shift gears, like a truck or bus driver did? I've never heard of, or seen such a setup. As far as I know, all RDC's had hydraulic torque-converter transmissions. All the engineer had to select was "drive", "neutral", or "reverse"....
 
railiner said:
Are you saying that the engineer had to shift gears, like a truck or bus driver did? I've never heard of, or seen such a setup. As far as I know, all RDC's had hydraulic torque-converter transmissions. All the engineer had to select was "drive", "neutral", or "reverse"....
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Yes this is my understanding. Shift of gears was a requirement of operation a RDC.

The power transmission of the original Budd RDC was its weak point. “Shift of gears” might not be 100% technical but it easy to understand.
 
Just-Thinking-51 said:
Yes this is my understanding. Shift of gears was a requirement of operation a RDC.

The power transmission of the original Budd RDC was its weak point. “Shift of gears” might not be 100% technical but it easy to understand.
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How did they operate in multiple units then?

Could you provide a citation stating what you are claiming? I have never seen anything that suggests that Budd RDCs use anything other than a hydraulic torque converter. This is documented for everything starting from RDC-1.
 
jis said:
How did they operate in multiple units then?

Could you provide a citation stating what you are claiming? I have never seen anything that suggests that Budd RDCs use anything other than a hydraulic torque converter. This is documented for everything starting from RDC-1.
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My statement was based on a Trains story about the RDC. The reference to a standard transmission is a way for people to understand it. Me bad trying to make think understandable to the masses.

There some very good master class about the Budd RDC none talk about the actual operation of said RDC.

I will poke around and see if I can find the original story.
 
railiner said:
Here’s one look at the controls…
https://www.google.com/search?q=con...ri#imgrc=jPGzqN-35VMEvM&imgdii=5xcy6a3mlozvlM
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Appears to be a 4 position throttle.
Note that a torque converter just provides the functionality of a clutch, i.e. allows some "slippage" between the prime mover and whatever is being powered. In a conventional automobile automatic transmission besides the torque converter there are planetary gears using bands that engage or disengage the gear set to provide the desired gear ratios.
I seem to recall back in the day riding the Reading RDC between Bethlehem and Philadelphia PA that once the train got up to speed there was a sensation of it shifting and the engine RPMs decreasing, so perhaps there was a gear change involved there. Unless it was just the engineer throttling back and coasting. It was a long time ago so my memory could be faulty.
 
Unlike the impression that @Just-Thinking-51 gave, the RDCs did not require manual gear shifting. It had a pretty standard arrangement with automatic shifting as described below.

You can find almost everything there is to know about the Budd RDC Systems in these documents:

Introducing RDC-1 - Budd

Budd Rail Diesel Car General Manual

BTW, scanning through the Railway Preservation News this is the best brief but concise description that I could find of the transmission system used in the Budd RDC:

Second, the transmission used on the Budd RDC was not a hydrostatic transmission; it was a heavy-duty version of the transmission used for many years in buses, a 2-speed planetary gearset. In low range the planetary gears rotate freely and power is directed through a typical torque converter to get the vehicle moving. In high range, the planetary gears are locked and the torque converter is bypassed, giving direct drive. The shift from low to high is accomplished automatically, but there is a momentary cutout of the engine as the shift takes place. Sound complex, but it was a relatively simple, bulletproof design.
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I rode on a train from Hakodate, Japan, on the island of Hokkaido, to Sapporo. That train was clearly shifting gears.
 
peteypablo said:
I rode on a train from Hakodate, Japan, on the island of Hokkaido, to Sapporo. That train was clearly shifting gears.
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Most diesel mechanical transmission do change gears, but they do so automatically. They use a system that is also used in buses and specifically many were adapted from drives used in second world war tanks. Specifically if they are DMUs they cannot depend on the driver manually changing gears. That is the issue being discussed, and not whether they shift gears or not.
 
So after spend way too much time looking into what happened to the Budd RDC.

The Original Budd RDC had a design that the operator would have to select gears. The as built cars had a 4 setting speed setting. The downfall of the origin RDC car was the first generation diesel engines, with a few other factors involved.

The SPV 2000 the high speed RDC had the transmission problem that cause it to fail, with a declining market.

Interesting statement that I came across was the RDC were only economical at two cars. If you need three or more cars a traditional engine with railcars was better.
 
The RDC only had 4 trottle settings no control of gears it had TC (transmission/clutch)and 1- 2 -3 as trottle settings accomplished by 3 throttle solenoids on engine.

the SPV had a stepless air trottle controlling engine speed between 90 and 110 lbs of brake pipe pressure, the transmission was 3 speed controlled by a 3 speed gear processor with no control by operator.
 
Dutchrailnut said:
The RDC only had 4 trottle settings no control of gears it had TC (transmission/clutch)and 1- 2 -3 as trottle settings accomplished by 3 throttle solenoids on engine.

the SPV had a stepless air trottle controlling engine speed between 90 and 110 lbs of brake pipe pressure, the transmission was 3 speed controlled by a 3 speed gear processor with no control by operator.
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Not saying how the power system worked on the SPV just saying it was a problem. While the original Budd RDC the engine was problematic, old 1st generation diesel with no support in the years after in parts.

The source Kalmbach % Classic Trains Magazine “Budd Rail Diesel Car”
 
Just-Thinking-51 said:
Budd RDC were problematic fresh out the factory. Completely amazing people are still trying to use them.

The problem or weakness was the transmission. Think an automobile standard transmission but harder to operate. If you missed a gear you would have to complete stop it to put it back in gear and start rolling again. Downshift for hills require, upshifting required for higher speeds. A lot of work. Unlike a truck when you can recover and float into gear. You match the rpm to the trucks speed to your gear input. A Budd RDC twin engine and twin transmission with or without additional RDC could not recover and had to stop to get it back in gear.

Surprised someone who truly wants to use these railcars, just has not gone to a traction motors with generators set up.

It was a bad design choice by Budd. So much potential but hard to operate, and high maintenance cost.
Click to expand...
I just got off the phone with a 81 year old retired B&O engineer who operated the B&O RDC-1's when they ran in the Baltimore Division (between Philadelphia PA and Brunswick, MD). The RDC-1's (and RDC-2's modified from baggage to a dining section) did not have any manual transmissions. The 550HP GM Detroit diesels were connected to heavy duty automatic GM hydraulic torque converter transmissions that powered one axle on each truck. They did not require shifting of gears unless the engineer needed to operate in reverse - same as a automobile or truck. My friend said they could get the RDC up to about 90mph on the section of track that went across the Monocacy River at the western end of the division. The B&O ran multiple unit trains (the "Daylight Speedliner" ran from Baltimore to Pittsburgh and return each day), and that required the 3 to 4 RDC's to be MU'd which was a standard feature for the RDC's, the same as all diesel locomotives. I rode the westbound Daylight Speedliner once in 1970 from Baltimore to Cumberland and returned on the eastbound Speedliner in the late afternoon.
 
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Here is a close up of a stripped control cab of an RDC. Notice the transmission/throttle control housing marked (FWD-OFF-REV) on the left side of the housing. The throttle is on the right side; the speedometer in the middle at the top. No shifting during normal operation other than stopping before shifting into reverse - the same as a motor vehicle.
http://imagestorage.nerail.org/photos/2008/06/17/2008061712270230504.jpg
 
I recall riding a diesel rail car on British Railways on a branch line in Cornwall around 1990 that had a manual gear shift of sorts. But my impression from riding RDC's was that they had an automatic shift.

I hope it's not too far off-topic to add that I had a fleet of HO scale RDC's that were rubber-band drive.
 
Even early model diesel-electric locomotives sometimes required a sort-of manual shifting called "transition"
 
Dutchrailnut said:
now your getting confusing , transition has nothing to do with gears or shifting, its reconfiguring the electric circuit to traction motors.
Series - parallel - and field shunting , the mechanical configuration does not change.
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As demonstrated by the fact that even electric streetcars and interurbans had transition from series to parallel and had no prime movers at all. In the older cars it was accomplished by lots of contacts on the controller going from full series to the first point of parallel.
 
Dutchrailnut said:
now your getting confusing , transition has nothing to do with gears or shifting, its reconfiguring the electric circuit to traction motors.
Series - parallel - and field shunting , the mechanical configuration does not change.
Click to expand...
I realise that, just mentioning it to show that early equipment of different types often required more manually operated controls than modern equipment.

Now if you want to see a “locomotive”, that actually did require shifting, clutch pedal and all, look no further than here…😁

https://web.archive.org/web/20060716072654/http://users.viawest.net/~bdwhite/rgstec14.htm
 

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