The Citroën-Kégresse P17 was a half-track artillery tractor produced by Citroën, based on the system developed by Adolphe Kégresse. The vehicle was used by the French, Polish and Belgian armies and a few captured by the Wehrmacht later.

Origins of the Kégresse saga

Adolphe Kégresse was a French engineer which pioneered the idea of lighweight, flexible tracks to be adapted on any type of common vehicle for better off-road performances, on soft ground, mud and snow. The generally good road network in France and good relations between France and Russia at the time meant French technician and inventor Adolphe Kégresse emigrated to Russia in 1905. Her became director of the imperial machine park, in St. Petersburg reporting to Tsar Nicholas II. There, he converted a serie of conventional cars, used notably by the Tsar in winter and for difficult terrain. Kégresse patented his system in 1913.

With the Russian Revolution however, Kégresse as the Tsar's protégé fled to Finland, then made its way into France. Her took all his plans and patterns wit him. His endavours were remarked by his friend and industrialist Georges Schwob d'Héricourt, which put him in relation with Jacques Hinstin, founder of the Hinstin car company, partner of Citroën. After a few Histin-Kégresse conversions, shown to André Citroën, the latter was impressed by their performance he immediately purchased Kégresse's patents, founding the Citroën-Kegresse-Hinstin company. The latter started converting all sorts of vehicles into half-tracks in the Citroën range.

In 1920 various prototypes were created based on the first experiences of Russia, based on the Citroën B2 car, and called "Type B". In 1921 Citroën started marketing the first series model K1, followed by the P4T in 1924, the P7T in 1926 and the P10 in 1928, all with a 4-cylinder petrol engine. This culminated woth the P15N in 1928, sporting a 6-cylinder engine and better suited for the Army needs.

Next came the P17/19 based on the Citroën AC6 chassis, with a shortened bonnet (more compact C4F engine) and simplified, lighter bodywork but useful loading space. The general structure was reinforced and simplified. In fact it was even thought to be dismountable for rail transport. All free spaces were used to create extra storage compartments, anchors for water cans, additional fuel tank to feed the engine with an electric pump. But the great novelty was its front roller helping in overcoming vertical obstacles. The unditching winch spoting a 80 m cable, which could be spun both front and rear was also an enormous adavantage. This became the ultimate "expedition car". It became Citroën's favorite when launching the "yellow cruise" in China and back.

Development

The Kégresse traction system in general replaced each drive wheel with running gear made of a rubber track plus two large wheels. The original suspensions were replaced, while the entire axle rested on a trolley, with rocker arms to maintain tension and four load-bearing rollers cushioned with vertical spring cylinders. In general, the main, large wheel forward was the drive sprocket, while the other aft acted as idler and tensioner for the rubber track. The track could always maintain contact with the ground and prevented the front axle from rising when overtaking an obstacle. Compared to tracked systems at the time, its lightness and relative silence were perfectly suite for reconnaissance vehicles, with the major drawback of a rapid wear of the rubber track: It was estimated replacement was needed after 2,000 km crossed, versus 6,000 km or more for metal tracks.

The P14 model was part of a family of Citroën-Kégresse half-tracks, also including the P17 and P19. All were acquired by the French Army mostly for tests, in the early 1930s as artillery tractors. They were also tested as troop transports and reconnaissance vehicles. They all shared the same "Kégresse-Histin" type track developed for the great trans-African raids of the 1920s used as advertising campaigns by Citröen, at the time the most famous and influencial French brands. Citroën capitalized on this to propose to the army a serie of half-tracks under the "P" typology. They were purchased in small quantities for testing purposes in various artillery units.

Production

Between 1930 and 1932 a small number of P14 were produced, widely tested as all-terrain artillery tractors. Similar to the P19, the P14 was however more powerful and heavier, with a reinforced undercarriage according to the Army's requirements. The P17 became the go-to light tractor half-track

Design

Design, 5 views.

The spar chassis was provided an unditching roller at the nose to overcoming obstacles and gap trenches. The front steering wheels were given for suspension semi-elliptical leaf springs whereas the the rolling train aft was of the "Kégresse-Hinstin" type. This system was directly evolved from the great trans-African raids of the 1920s. Each track comprised a front driving wheel, rear idler wheel on a balancer, and two two-wheeled carrying trolleys connected to the rear axle. They were almso suspended by semi-elliptical leaf springs. The was also a unique inverted track support roller. The P17 was powered by a compact 2,655 cm³ Citroën six-cylinder petrol engine mounted forward and rated for 42 HP. Behind the open driver's cab a tarpaulin could be fitted over the rear troop compartment, with a transversal bench large enough for 4 crew members facing backwards.

The P17 integrate all important aspects of the C4 and its engine is an evolution of the 1,628 cm3 (72x100). Its rear axle was fixed unlike the P10 in a flexible way, o enable vertical leeway.

Evolution and variants

The P17 was manufactured for more than 5 years, but gradually evolved. The P17A was successeded by the P17B. They shared the same C4 base but rused the B15 truck chassis, itself derived from the B14. Its Weight empty, without bodywork was 1,200 kgs. The P17C was revealed in 1932, and it was powered by the C4G engine, which developed a 1,767 cm3 (75x100) capacity. At the same time, the P17s obtained a brand new chassis designed for its purpose, flat and without the slung shape at the rear and far more robust, ported to 1,470 kgs empty (engine, transmission, but no bodywork).

The P17C was followed by P17D and P17E only marked by minor modifications. The P17 of all Kegresse tractors is the model seeing by far the largest production by Citroën. For the French army alone, more than 1,700 P17s were delivered and Citroën marketed it to other countries as well. Poland made its own version, and Belgium and Denmark both evaluated it. But the P17 model was also used in forestry services and for agriculture or public works as well.

The P17 in service

The French army used 1,442 P17 halftrack tractor as listed by September 1939. They were used a prime movers for the 25mm AA guns, 47mm AT guns and 75mm AT and field guns. The P14 entered service at first for extensive tests, deployed in various infantry units which needed an all-terrain tractor. Production numbers were indeed way too low to fill the role of light artillery tractor everywhere; Other, cheaper and simpler vehicles were tasked for the same. Thus, the vehicle was mererly a droplet among vehicles fielded by the French Army between the hexagon and far flung colonies.

Polish P14s

At the start of 1931, France also agreed to deliver 94 Citroën-Kégresse P14, P17 and P19 half tracks to Poland, delivered between May 1931 and December 1933. They were extensively tested and used as artillery tractors as well as liaison vehicles or to install field telephone lines. Polish P19s saw action in 1939, towing the massive 120 mm Armata WZ gun as well as the 155 mm wz. 1917 howitzer.

Belgian P14s

In 1934 the P14 was also purchased by Belgium, producing afterwards a local variant called the FN-Kégresse 3T.

In German Service

Vehicles captured by the Wehrmacht after the surrender of France were returned to service and redesignated Transportkraftwagen Ci 306(f) for the P14, although P17 were more numerous. They were not declined into specialized variants or armoured due to their weak chassis, but used in the same role as the French vehicles. These were among the very few non German half-tracks in service at the time, and disappeared in the furnace of 1944 combats in France.

As of today, the vehicle did not survived. It had a controversial legacy, being very slow, especially when towing a heavy payload, certainly unfit for rapid manoeuvers and motorized units. As a general disinterest of the army for half-track (but De Gaulle and a few officers), France, while being a pioneer in the 1920s, was provided very few of these vehicles when the war broke up. The flexible, lightweight Kégresse track system however would have a considerable impact technically, being purchased by White in 1939 for its legendary M2 and M3 Half Tracks Cars, also used ironically by the Free French Army...

Specs P17
Dimensions:	4.38 x 1.69 x 2.09m ()
Total weight, battle ready:	1,85 t
Useful load:	Live load 0.7t + towed load 1.3t
Crew:	2+4, see notes
Propulsion:	4 cylinders, 1770 cm3, 31.5 hp at 2800 rpm
Speed:	32 km/h
Range (road/off road):	c200km
Production	1,442

Links/Src

P16 on tank-afv
kegresse.dk/
loutan.net/
forum.axishistory.com/
forum.axishistory.com Polish C4
derela.republika.pl/
www.1939.pl/
doublechevron.de
armyvehicles.dk/
/it.wikipedia.org
Citroen P28 on TE

Illustrations

Citroën-Kégresse P17


P17 tractor for the 75 mm Field Gun


P17 tractor for the 47mm APX

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ASPHM - Autochenille Citroën Kegresse P17

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Sd.Kfz 2, 6, 7, 8, 9, 10 and 11 were half-tracks designed just before the war as prime movers, to carry supplies, ammunition, personal, and tow artillery. Many were also converted during the war as armored versions carrying AA FLAK guns (Flakvierling, 37 mm, or the legendary 88 mm Rheinmetall als used as tank hunters), or were converted as nebelwerfer (rocket launching armored vehicles). They were built by Hanomag, Steyr, Mercedes-Benz, Bussing and many other manufacturers until 1945, over 20,000 half-tracks.

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