Le Roi Company During World War Two
West Allis, WI
1913-1916 - Milwaukee Machine Tool
1916-1954 - Le Roi Company
1954-1967 Le Roi Division of Westinghouse Air Brake Company
1967-1972 - Pneumatic Equipment Division of  Westinghouse Air Brake Company
1972-1991 - Le Roi Division of Dresser Industries
1991-1996 - LeROI Internatinal, Inc.  Privately Owned
1996-2005 - CompAir LeROI, Inc. of Comp Air Group
2005-2017 - LeRoi Gas Compressors of a Ohio Investor Group
2017-Present - Part of the Gardner-Denver Industrial Division

This page updated 11-27-2024.

As the above information in the title shows, the Le Roi Company of the World War Two era has undergone many ownership changes since 1954.  Originally formed in 1913 as the Milwaukee Machine Tool to produce gasoline engines, the company was reorganized by Mr. Charles W. Pendock as the Le Roi Company.  The new company also produced gasoline engines and added air compressors to its business portfolio.  During World War Two, the Le Roi Company built at least 10,000 gasoline-powered air compressors for both the U.S. Army Corps of Engineers and for the U.S. Navy.  Most likely the Navy's purchase of Le Roi Air compressors was for its Naval Construction Battalions, otherwise known as the Seabees.  The company also produced five different power units for the U.S. Army Signal Corps during World War Two.

In 1954 the Le Roi Company was sold to the Westinghouse Air Brake Company.  In 1958, the gasoline engine portion of the company was sold to the Waukesha Engine Company.  There after, Le Roi would only produce air compressors for the many different companies that owned it. 

This advertisement was featured in the May 1917 edition of Commercial Vehicles magazine.  Note that the address is shown as being in Milwaukee, WI.  Later this would change to West Allis, WI.  Image courtesy of Warren Richardson.

Le Roi Company's World War Two Products:  Table 1 and Table 2 show that the Le Roi Company had two factory locations during World War Two.  My research was only able to identify the one plant at Mitchell Street and 60th Avenue in Milwaukee, WI that later became Mitchell Street and 68th Avenue in West Allis, WI.  It is my contention that the plant locations in both Table 1 and Table 2 are the same plant.  Due to the confusion over the address change, contracts were being sent to what the military believed to be two different Le Roi, plants which was in fact one plant that had its address changed.

Therefore, if the two totals are added together from Tables 1 and 2, the Le Roi Company had $46,895,000 in total major contracts during World War Two.  Table 3 shows that its Greenwich, OH plant had $198,000 in mower contracts from both the U.S. Army and U.S. Navy.

The GMC AFK-352 1-1/2-ton 4x4 was the first truck that carried the Le Roi compressor unit.  Le Roi Company produced a total of 819 of these for the Army Corp of Engineers from July 1940 through May 1941.  These units most likely were produced under the first three contracts in Table 2.  These were the contract numbers 978-ENG-1439 for $1,210,000, 978-ENG-4950 for $1,209,000, and 978-ENG-1822 for $977,000.  If all three contract amounts are added together, this gives a total of $3,396,000.  Dividing by 819 gives an average cost of $4,417, which is higher than the costs associated with the contracts in Table 4.  This is reasonable for a first production run of a new product.  Image courtesy of Jeff Lakaszcyck added 11-27-2024.

The Army Corps of Engineers found that the 4x4 trucks were underpowered, top heavy, and did not do well in off-road conditions.  The Army engineers pulled a Le Roi compressor unit from a 4x4 truck and mounted it on a CCKW 2-1/2-ton 6x6.  After testing, it was found to be better suited for the application, and the Army Corps of Engineers began ordering Le Roi compressor units on the GMC CCKW truck chassis. 

There is always the one-off of a vehicle that is not part of the normal production series.  In this case, it is a Studebaker model US6 2/1/2-ton 6x6 truck with a Le Roi Model 105 GA air compressor unit.  This 1941 photo taken at Fort Benning, now Fort Moore, shows Army Corps of Engineers soldiers utilizing the compressor to inflate a pontoon for a river crossing.  This was a typical application of the Le Roi compressor trucks during World War Two.  There was always another creek or river to cross.  Image courtesy of Jeff Lakaszcyck added 11-27-2024.

As a side note, the information sheet above also shows that the Sullivan Machinery Company of Michigan City, IN also supplied air compressor trucks.  Sullivan produced 79 units mounted on Marmon-Herrington Company four-wheel drive trucks produced on West Washington Street in Indianapolis, IN. 

Table 4 shows that according to TM 5-5060 the Le Roi Company produced at least 9,606 compressor units for the U.S. Army Corps of Engineers.  However, there are still two Army Corps of Engineer contracts that are not identified with a number of compressor units.  Also, the U.S. Navy had four contracts for air compressors.  No doubt the Le Roi Company produced over 10,000 compressor units to help win World War Two.

Another product line of the company during World War Two was generator sets for both the Corps of Engineers and the Army Signal Corps.  Le Roi built five different types of power units for the Army Signal Corps incorporating its gasoline engines with generators furnished by two other companies.  Electric generators were not a Le Roi product line. 

The data lines in Tables 1 and 2 marked in dark gray are those that match contracts in Table 4.

TM 5-5060 shows the Model 105 GA mounted on a GMC CCKW truck.  This is how the air compressor unit is most commonly portrayed. 

The Model 105G compressor could also be mounted on a skid.

The air compressor could deliver 105 CFM at 100PSI.  The clutch was provided by the Twin Disc Clutch Company of nearby Racine, WI. 

This image from TM 5-5060 shows the tool arrangement in the storage bins on each side of the vehicle. 

This lists the tools stored onboard the vehicle. 

Compressor Trucks:  Below are the GMC CCKW trucks I have found with Le Roi compressor units on them. Actually, they are a rather rare item.  I have only been able to find three in fully restored condition.  

This Le Roi compressor truck is on display at the National Museum of Military Vehicles in Dubois, WY.  Author's photo.

During my visit, I was able to view and photograph both sides of the compressor unit.  This and the next three photos are of the passenger side of the Le Roi-built unit.  Author's photo.

Author's photo.

Author's photo.

Author's photo.

The compressed air surge tanks were built by the Pressed Steel Tank Company, also of West Allis, WI.   Le Roi's use of the Pressed Steel Tank Company was a logical choice, as the two companies were only three tenths of a mile apart from each other in West Allis, WI.  Author's photo.

The next two photos are of the driver's side of the unit.  This side contains the gauges for the compressor.  Author's photo.

The red data plate on the cranking motor indicates it was built by the Delco-Remy Division of General Motors in Anderson, IN.  Author's photo.

 Shown here in better detail are both the Delco-Remy cranking motor and the handle to the Twin-Disc clutch.  Author's photo.

 Author's photo.

This engine is a later model than shown in the information above from TM 5-5060. This is a D471 engine with a serial number of 37X1552.  The serial number is also of a different sequence than those shown in Table 4.  Author's photo.

This excellent example of the Le Roi air compressor truck is on display at the World War II American Experience Museum in Gettysburg, PA.  Author's photo.

The museum has a complete set of the tools on display that were part of the compressor truck's equipment.  This is the only place I know of where this equipment can be seen.  Author's photo.

 Author's photo.

 This image shows the wooden work bench that pulls out from behind the truck's cab.  Author's photo.

Author's photo.

Author's photo.

Author's photo.

 The World War II American Experience Museum also has a Le Roi compressor truck in operating condition.  Here are several photos of it located in the museum's motor pool.  Author's photo.

Author's photo.

Author's photo.

Author's photo.

This is the same vehicle on display at the 2019 MVPA national convention in York, PA.  Author's photo.

Author's photo.

Author's photo.

Author's photo.

Author's photo.

Author's photo.

 The World War II American Experience Museum also has a Le Roi compressor truck awaiting restoration.  Author's photo.

Author's photo.

Here is another Le Roi compressor truck awaiting restoration in Pennsylvania.  This truck is part of the Bill Hallett collection.  Image courtesy of Warren Richardson added 11-27-2024.

Image courtesy of Warren Richardson added 11-27-2024.

Image courtesy of Warren Richardson added 11-27-2024.

This GMC 1941-1942 CCW 6x4 was photographed at the former AAF Tank Museum in Danville, VA minus its outer back wheels. This particular example has a Le Roi air compressor mounted on the bed.  However, there is no engine with the unit.  This particular unit, as can be seen, was for sale when I last visited the museum in 2019.  Author's photo.

In 2023, the AAF Tank Museum went out of business and sold all of the vehicles in the facility.  Among those items auctioned off was this CCW and 119 tanks and armored vehicles.  It was quite the place to visit for the 20 years it was open in Danville, VA.

The museum has the CCW misidentified as a 1944 CCKW.  Starting in August 1942 through spring of 1943, the hardtops were being replaced by soft top cabs. Also, GMC only ran the 6x4 CCW from late 1941 to late summer of 1942.  During this period 23,501 were built and shipped overseas under Lend-Lease.  Author's photo. 

Author's photo. 

Author's photo. 

Signal Corps Power Units:  While Le Roi is best known for its World War Two compressor trucks, it also had three U.S. Army Signal Corps contracts for power units.  The following five power units have Le Roi gasoline engines in them, either a D471, a D382, or a D384. Either Westinghouse or General Electric furnished the generators.  Le Roi then assembled both the gasoline engine and generator into the finished power unit.

Post World War Two Era Le Roi Truck Engines: 

This advertisement for a Le Roi truck engine application is after it became part of the Westinghouse Air Brake Company in 1954. Image courtesy of Jeff Lakaszcyck added 11-27-2024.

Autocar used Le Roi engines in its Model CL-8564 truck line.  Image courtesy of Jeff Lakaszcyck added 11-27-2024.

The Le Roi West Allis Factory:  The 1910 and 1927 Sanborn Map shows the Le Roi factory at Mitchell and 60th Streets.  The Google Maps show that it is located at Mitchell and 68th Streets.  Sometime after 1927 the north-south roads were renumbered, resulting in the address change.

This 1910 Sanborn Map shows the Milwaukee Machine and Tool Company being located at the corner of Mitchell Street and 60th Avenue in Milwaukee at this early date.  Image courtesy of Tim Wright added 11-27-2024.

This 1927 Sanborn Map shows the Le Roi Company factory at Mitchell and 60th Ave.  The plant went under a considerable expansion in the intervening seventeen years. 

This hurts!  Actually, this hurts really bad!!  It is always so sad to see an old factory torn down which housed a company like Le Roi that did so much to help win World War Two.  This September 2014 Google Maps photo shows the plant being razed from the inside out.

Image courtesy of Google Maps. 

The steel sheeting on the sides of the building is a newer update to the factory which was of brick construction.  The wrecking crew had not yet gotten to the office entrance when the Google Maps vehicle came by.  Image courtesy of Google Maps.

The last occupant of the building was Metal Technologies.  Image courtesy of Google Maps.

What is interesting about the Google Maps is that if one does a street view down 68th Avenue, one finds the images above like this one.  Image courtesy of Google Maps.

However, if one does a street view from Mitchell Street it shows an empty lot where the Le Roi factory used to be.  The Google Maps vehicle last came down Mitchell Street in November 2018.  Image courtesy of Google Maps.

This shows the same intersection in 1945.  Note that the building is of brick construction. 

Image courtesy of Google Maps


This 2024 Google Earth view shows that a new medical arts building with a parking lot has been erected on the former Le Roi Company factory location.  

The Le Roi Greenwich, OH Factory:  Le Roi Company at some time before World War Two purchased the Central Tractor Company of Greenwich, OH.  The Sanborn Map below shows this plant in 1921.  This plant produced lawn mowers for the war effort.

Image courtesy of Sanborn Maps.

A current Google Earth satellite view shows the plant is still there and now occupied by Adams Small Engine.  The company's website shows it as a re-seller of used lawn mowers and garden tractors.