The Berliet GD series is a range of medium/heavy commercial vehicles chassis produced by the French manufacturer Berliet from 1926 to 1953. It includes normal (the vast majority) and forward control designs. The GD series (with universal joints connecting the wheels and transmission) was introduced to replace the CBA and derivative models (which used chain drive) in the intermediate segment (between the lightest and heaviest segments) of Berliet rigid vehicles. The GD series had limited military use as a not-armoured transport vehicle both with purposely-made models and through requisition.
The GD series was replaced by the GL series of commercial vehicles.
History 1926–1934: GDH, its evolutions, and first diesels
In 1926, Berliet began the GD series of medium duty trucks, rigid lorries (designated by the G) with universal joint transmission to gradually replace the CBA series and derivatives which used chain drive transmission. The first GD series was the GDH, a commercial chassis with a 5 tonne payload and an 11 tonne gross vehicle weight (GVW). Its engine, codenamed MLB, is an inline-four petrol engine with a 110 mm bore and a 140 mm stroke, giving a displacement of 5,322 cc. It was rated at 20 fiscal horsepower (CV). The chassis was offered in two lengths and has double wheels on the rear. The French magazine La revue industrielle gives an alternative name for the GDH: CBL. In May 1927, Berliet introduced a GDH version more focussed on coach usage, the GDHV with a 10.5 tonnes GVW, using various evolutions of the MLB engine, with the same bore/stroke/displacement ratio (MLBC, MLBD, MLB5 and MLB6).
In November 1927, the company presented the GDHM, an evolution of the GDH with the same payload and a 12 tonnes GVW. It was initially delivered with the MLB5 engine. As was the case with its predecessor, the GDHM had two lengths, with wheelbases of either or . The wheels are either solid or pneumatic and double on rear. Brakes are of two types: servomechanical actioned by a pedal (for the front wheels) and mechanical actioned by a lever (for the rears). In February 1928, Berliet launched a GDHM with reinforced chassis called the GDHMB, increasing the payload to 7.5 tonnes, 13.5 tonnes GVW. It had a version for dumpers with a derated engine, the GDHMB2. In August 1929, Berliet launched yet another GDHM derivative, the 12 tonnes GVW GDHP, basically the same chassis but with an inline-six petrol engine codenamed as MLPC3. The MLPC3 has a 125 mm bore and a 140 mm stroke giving 10,308 cc. The chassis also received a different inline-six engine with a 110 mm bore and a 140 mm stroke, being marketed in this case as GDHPB. Other derivatives followed: in 1930, the 11.5 tonnes GVW GDHL with the MLBC 110 engine, a derated MLB5; in 1931, the 17 tonnes GVW GDHE with the MLB5 as well as a gasifier-equipped GDHM and a GDHE with a more powerful MLB5 variant (MPA) marketed as GDHE 28 (the number making reference to the fiscal power). Many of the petrol-engined GDs introduced from then on would include the fiscal power in their name.
In February 1932, the GDHM received the MKU 110 engine, an inline-six petrol with a 110 mm bore and a 150 mm stroke giving 8,553 cc, and was reclassified at 6 tonnes payload and 13.5 tonnes GVW.
By 1931, Berliet began fitting diesel engines on its CBAC lorries, using Acro technology licensed from Bosch. In March 1932, various vehicles of the GD series mounted the MDB, an inline four diesel with 120 mm bore and 160 mm stroke, giving a displacement of 7,238 cc and rated at 28 CV (actual power and later ). Those first vehicles were variants of the GDHM, GDHMB and GDHE, initially distinguished from the existing petrol variants by adding a to the names (making reference to the fiscal power). By late 1932, the number alongside the letters started making reference to the engine displacement in litres, which would become common practice for diesels. The MDB-powered models were identified by a . Between September and October 1932, two new six cylinder diesel engines appeared: a variant of the MDB called MDE (10,857 cc, rounded to 10 litres) with a power of and the MDC of 110 mm bore x 150 mm stroke (8,553 cc, rounded to 8 litres), . These resulted in some new models: GDHMB 8 (15 tonnes GVW), GDHM 10 (13 tonnes GVW) and GDHE 10 (16 tonnes GVW). By that time, several petrol variants with six cylinder engines were also marketed: GDHM 22, GDHM 25, GDHMB 25, GDHMB 30, GDHE 28 (again, the number indicating fiscal power).
In February 1933, Berliet introduced the GDHE 12 (16 tonnes GVW) with the MDH engine, an inline-six diesel 130 mm bore x 160 mm stroke (12,742 cc, rounded to 12 litres) with an actual power of . By that time, the GD series was the middle range of Berliet's commercial chassis, between the lighter V series and the heavier GP series.
Various GDs shared specifications. All the diesels and most petrols generally have the same, rectangular profile cabin cell, with two doors opening from the rear side (as most vehicles today) and whose roof forms a projection acting as a sun visor above the windscreen. Only the bonnet's length, which opens like a butterfly wing as on all trucks of the time, differs depending on the type: the longer six cylinders are recognisable by their two-part bonnet sections. All GDs were delivered with 4-speed manual gearboxes, rear-wheel drive, and leaf spring suspension. By the early 1930s, servomechanical brakes on the four wheels were standard. Also by that time, the bodywork was slightly updated, with minor changes as the addition of a front bumper (early models do not have one).
From the GD series chassis Berliet started to develop tractor units as the 22 tonnes gross combined weight (GCW) TDH of 15 tonnes payload or the 28 tonnes GCW TDHE of 20 tonnes payload. (both MDE engine).
1934–1939: new chassis designs, diesel expansion and gasifiers For 1934, Berliet introduced the GDL, a 5 tonnes payload chassis similar to the GDHM aimed at replacing the GDHL. It was initially offered in four variants unveiled through the year: GDL 20 (10.5 tonnes GVW, MLB6 engine), GDL 22 (10.5 tonnes GVW, 22 CV four cylinder MKB engine), GDL 7 (12 tonnes GVW, MDB engine) and GDL 8 (11 tonne GVW, MDC engine). By 1934, Berliet added air brakes by French Westinghouse as an optional for GD models.
In February 1934, Berliet introduced the GDE 10 (replacing the GDHE), a chassis for construction usage, and the GDM 10 (replacing the GDHM and the GDHMB), both 15 tonnes GVW, MDE engine. In March of that year, the GDM 7 (15 tonnes GVW, MDB engine) and three chassis for construction: GDE 7 (15 tonnes GVW, MDB engine), GDE 12 (15 tonnes GVW, MDH engine) and the GDE 14. This last one was equipped with a new diesel engine, the six cylinder MDK, a longer stroke version (180 mm) of the MDH.
By May 1934, Berliet introduced two low chassis with diesels for coach usage: GDSM 7 (15 tonnes GVW, MDB engine) and GDSL 8 (13 tonnes GVW, MDC engine). At the same time, the company launched two low chassis for heavy delivery vans: GDSM/GDSE 10 (15/16.5 tonnes GVW, MDE engine) and GDSM/GDSE 12 (15/16.5 tonnes GVW, MDH engine).
In early 1935, Berliet launched the GDM 12 (15 tonnes GVW, MDH engine) and the GDM 21G (the G indicating the MKUG engine, a gasifier-equipped version of the six-cylinder MKU petrol engine). The GDMs would become the heavier tonnage GDs. In July, the GDLH 10 (12 tonnes GVW, MDE engine) and GDM (15 tonnes GVW, 25 CV MKU engine).
The Acro-based diesels had reliability problems, so, in 1935, Berliet took the Ricardo licence for diesel engines' direct injection. The previous French licensor, Citroën, had dropped it because of technical and financial difficulties. The Ricardo technology was tested on a MDK engine with three combustion chamber systems: Whirpool, Comet II and Comet III. The Ricardo-based engines had the same failures. The problem only was fixed when Berliet made changes to the cylinder heads.
In 1936, Berliet presented the first chassis powered with Ricardo's technology, the GDLR 7 of just over 12 tonnes GVW. The GDLR 7's engine was named as MDBR ( for ), an inline four diesel with 120 mm bore and 160 mm stroke, giving a displacement of 7,238 cc and rated at 28 CV. The company also unveiled a similar Acro type chassis alongside it, the GDLB 7 (MDB engine). That same year, the company launched an 11 tonne GVW version of the GDL called GDB 22, powered by the MKU 3, a 22 CV inline four petrol 110 mm bore x 155 mm stroke (5,892 cc). The GDL 10 (12 tonnes GVW, MDE engine) was added. The GDR 22 (5892 cc MKB 3 engine) replaced the GDL 22 (the GDRs would start to replace the GDLs in the lower tonnage GD series).
In mid-1936, Berliet launched the GDLK 7, the first Berliet with a modern, proper forward control cabin (the "K" signalling it). The chassis was first with an MDB engine and later with an MDBR. This initial GD series forward control cabin design adopted features that gradually were introduced and became standard in the normal control cabins between 1936 and 1937 and were so for them until they left production: removal of the "sun visor", doors opened from the front side, chromed grille frame (this was already present in some models), trapezium-like instead of rectangular side profile for the cabin cell. Later that year, Berliet put on sale two other models using the same forward control cabin: GDRK 22 (over 10 tonnes GVW, MKB 3 engine) and GDMK 10 (over 15 tonnes GVW, MDE engine).
In late 1936, at that year's Paris Salon, Berliet unveiled the GDLR 8 chassis with the MDCW engine. The MDCW was a MDC using Ricardo's Whirpool system. The same engine was later offered as MDC 2 C (Comet II system) and MDC 3 C (Comet III). At the same Salon, Berliet also presented the GDR 7 (MDBR engine). This new chassis was offered in two lengths: normal (10.8 tonnes GVW) and long (11 tonne GVW). The GDR 7 would become the most popular civil model of the GD series before World War II. Finally, there was the forward control GDSL (13 tonnes GVW), a low chassis mainly for coach/bus usage, with two versions: GDSL 30 (MKU 110 petrol engine) and GDSL 8 (initially, MDCW diesel engine). The GDSL initially had a single seat cabin similar to the contemporary Renault ZP. Also in that year, the company launched the GDM 8, a chassis with a GVW of either 15.6 tonnes (normal) or 15.8 tonnes (long), powered by the MDCW and later by the MDC 2 C. The GDM 8 was the heaviest four-wheeler Berliet in 1936. There was another two forward control models: GDMK 7 R (over 15 tonnes GVW, MDBR engine of second generation or MDB 2R) and GDRK 7 (about 11 tonne GVW, MDBR engine).
In 1937, the models were the GDSL 7 (11.5 tonnes GVW, MDBR engine of second generation), and the gasifier-equipped GDMG 2 (16.5 tonnes GVW, MKUG engine) as well as two forward control reinforced chassis versions of the GDL and the GDR respectively: the GDRKL 7 (14.5 tonnes GVW, MDBR of third generation or MDB 3R) and the gasifier-equipped GDRKLG (15 tonnes GVW), powered by the MPB 2 G, a gasifier-ready derivative of the MDB engine. By this time the forward control cabin of the GD series was modernised, with more rounded lines and a more integrated grille while the normal control ones kept the previously described design. By the end of the year, it appeared another forward control chassis (GDLK 8) and a heavier GDR 7 (GDRC 7). In 1938, the company launched gasifier-equipped chassis: GDL 21G, GDLCG 21, GDR 21G (all powered by the MKUG). It presented the GDME 7 (16.5 tonnes GVW, MDBR engine of third generation) and the GDR 8 (about 11 tonne GVW, MDC 3 C engine). The company also made changes to various chassis, mostly increasing GVW. Those chassis added the sufix .