Tuesday, December 14, 2010

Baldwin - BLH 600 series engine history

THIS CONTENT was originally published on my locomotive site a number of years ago. I've decided to put it back on the net on our new site. I have totally cut and pasted it from my own site page at the internet archive but the PHOTOS are not included. I will try to get all of those, and some more, including shots we have of some of the prototype engines that haven't seen the light of day before, up on this blog in the near future. So please ignore photo references in the text.

Baldwin / Baldwin-Lima-Hamilton 600 series diesel engines 1946-1956.
Following the failure of its multi-engined road locomotive concept, which effectively ended the Baldwin 400 series engine's future, the company decided to center future locomotive production around a thoroughly redesigned version of the VO engine, to be known as the 600 series. Paramount to the new engine's design was the ability to accept turbocharging; the cylinder heads had to be totally redesigned to eliminate the integral combustion chambers of the VO in favor of the modern open chamber design (in which fuel is injected directly into the cylinder volume.) New, saucer-top pistons were developed. The entire engine structure was redesigned and reinforced, including much heavier crankshaft and connecting rods; the new engine would be required to develop a rated 1500 HP, which was 150% of the rating of the previous 8-cylinder VO.

The new engine series was phased into the various locomotive lines in a slightly hodge-podge manner. The basic details of the new engine lineup immediately after the end of the Second World War are seen below. Note that all 600 series engines were 12.75" bore, 15.5" stroke and ran at 625 RPM maximum.

606NA 6 cylinders, normally aspirated. BMEP = 70.6 psi. 660 brake HP.

608NA 8 cylinders, normally aspirated. BMEP = 80 psi. 1000 brake HP.

608SC 8 cylinders, turbocharged (Elliot BF44.) BMEP = 120 psi. 1500 brake horsepower. (This engine is pictured at left, in its earliest production configuration. From Baldwin Diesel Engine Manual DE-100, published 1946 and revised 3-26-47, 4-9-47, 2-1-48, 5-1-48.

Baldwin decided, shortly, to replace the 608NA engine with a new, turbocharged 6-cylinder engine. This engine is added to the aforementioned DE-100 manual in the 3-26-47 revision; details for it are as follows.

606SC 6 cylinders, turbocharged (Elliot BF40, known as "two exhaust pipe" type, or Elliot BF34, known as "three exhaust pipe" type.) BMEP = 106.7 psi. 1000 brake HP.

It should be noted at this time that Baldwin was advertising and rating its locomotives based upon the brake horsepower rating of the diesel engine. ALCO-GE was also using this system with its locomotives powered by 539 engines, but had decided to rate its road locomotives, powered by 244 engines, using the "horsepower for traction" rating which indicates power delivered to the generator. This theoretically placed Baldwin at a slight power disadvantage, which it eventually corrected later.

The original DE-100 manual stipulated that main bearing alignment be checked at intervals of once per year, or every 300,000 miles. The revision of 5-1-48 shortened this to every six months or 50,000 miles. The 5-1-48 revision becomes more specific about procedure of mounting the generator to the engine and checking its alignment. The engines were still using shimmed main bearings at this time; drawing D-1004 in DE-100 shows the comparative placement and thickness of the bearing shims. Some of the locomotives still used lube oil radiators; some used the full flow oil filters, some the bypass type. The 2-1-48 revision appears to be the one to include the three-pipe, or BF34, turbocharger for the 606SC. In general, it is clear that, at this time, the engine had been improved from the VO, but many design details were being altered in the period 1946-1948 and that some of the original sources of complaint (oil radiators, shimmed crankshaft bearings, for example) had still not been eliminated when the 600 series engine appeared.

Baldwin Diesel Engine Manual DE-104 was the next manual issued, and while the first printing date is not known, it was revised in 5-15-50 and 11-1-50. It is assumed that the original printing was likely in late 1949 or early 1950. In this manual, it is made apparent that numerous changes have been made to the engines. Probably the most important to modern railfans, and the least known, is the fact that Baldwin changed over at this time from rating its locomotives by the brake horsepower of the engine to rating the locomotives using the newer "horsepower for traction" method. Baldwin increased the actual power output of the engines without altering the advertised ratings of the locomotives. Below are the 1950 specifications for the three engine models in production (first built in January 1950 and contained in DE-104 on a revision page dated 5-15-50.)

606NA 6 cylinders, normally aspirated. BMEP = 88 psi. Compression ratio 14.88:1. 825 BHP. HP for traction 750.
606SC 6 cylinders, turbocharged (as before.) BMEP = 120 psi. Compression ratio 13.45:1. 1125 BHP. HP for traction 1000.
608SC 8 cylinders, turbocharged (as before.) BMEP = 130 psi. Compression ratio 13.45:1. 1625 BHP. HP for traction 1500.

New, Tri-Metal shimless crankshaft bearings replaced both the (shimmed) gridded and babbitt types used prior. Bearing dimensions remained the same, as did valve dimensions in the cylinder heads. The following are the given cylinder conditions at full load: 606NA max compression pressure 540 psi, max firing pressure 1015 psi. 606SC max compression pressure 720 psi, max firing pressure 970 psi. 608SC max compression pressure 750 psi, max firing pressure 1000 psi. Maximum exhaust elbow temperatures in the same order were given as 950, 850 and 900 degrees; thus, the normally aspirated engine had the highest exhaust elbow temperature. Valve timing for the engines depended upon whether or not they were turbocharged, and also upon whether or not the engines had the older "Saucer top" pistons with a concave piston crown, or the new "Hesselmann" pistons, sometimes referred to in the field as "Mexican Hat" pistons, as these had a depressed top portion with a pointed, raised center. Fuel injection timing also differed between piston types as well. Thus, for six-cylinder engines there would have been four different camshafts available (normally aspirated with saucer pistons, normally aspirated with Hesselmann pistons, turbocharged with saucer pistons, turbocharged with Hesselmann pistons.)

Baldwin issued its Diesel Engine Manual DE-111 on 9-15-50, which covered the next round of revisions to the 600 engine. The largest change was the inclusion of a substantially larger and heavier crankshaft; all of the bearing bore sizes increase, and lifting weight of the crankshaft increases as well. It appears that upon issuance, Baldwin was beefing up the bottom end of the engine to accept a further power increase. This happened shortly thereafter. The following ratings are included in this manual, on a page dated 6-15-51.

606 6 cylinders, normally aspirated. BMEP = 93.5 psi. 875 BHP. HP for traction 800.
606A 6 cylinders, turbocharged (Elliott H503.) BMEP = 140 psi. 1315 BHP. HP for traction 1200.
608A 8 cylinders, turbocharged (Elliott H704.) BMEP = 140 psi. 1750 BHP. HP for traction 1600.

Cylinder conditions at full load are given as follows: 606 max compression pressure 540 psi, max firing pressure 1120 psi. 606A and 608A max compression pressure 690 psi, max firing pressure 1120 psi. Max exhaust elbow temperature 1000 degrees F for normally aspirated engine, and 925 F for turbocharged engines. The increases in power over the time the whole 600 series was in production had been produced by increase in fuel injection amount, involving both volume and timing, as well as boost pressure and thus scavenging effect and compression pressure. No increase in engine speed was needed to increase from the 1000 brake horsepower of the 608NA all the way up to the 1750 brake horsepower of the 608A.

At the very late date in Baldwin history of 2-1-55, manual DE-111A was issued to cover further revisions to the engine. These changes were very slight -- including changes to the crankcase breather design, engine air filter design, and others. One change of note was that the engines themselves became several hundred pounds lighter, for reasons which are not explained. This manual is also the first to contain a complete section on engine speed control applicable to all optional setups, including both types of air throttles available (D-1 and CE-100) as well as the 8-step electric throttle, and also includes data for the UG-8 and PG types of Woodward engine governors. (Most Baldwin manuals are specific, and thus there is a wide variation of manuals --- this is why this one, applicable to any optional combination, is unusual.) Looking through this manual reveals that the vast majority of important changes had already occurred prior to a date of 1953 (some of the pages in this manual carry this date) and most likely all of the last-generation changes physically date to 9/50, with the last uprating likely 6/51.

There you have it -- the complete breakdown of important evolutionary changes to the post-War Baldwin / Baldwin-Lima-Hamilton 600 series diesel engine. It is apparent that Baldwin continuously tried to improve their product, but for too many railroads it was not enough. Even though the late locomotives were greatly improved in reliability, the serious shortcomings of the VO and very early 600 engines caused many railroads to abandon Baldwin as a serious supplier of diesel locomotives.

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