Two-speed Axles in New Mercedes Models
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REE new Mercedes-Benz goods iassis, which with production options up a total of 63 versions, have been duced by Daimler-Benz A.G., StuttGermany. All are four-wheelers, able with either semi-forward or !orward control, two of them being I for 12 tons gross and one for tons gross. An interesting innova
is a Daimler-Benz two-speed rear for use with vehicles in the new eaviest of the new vehicles is the 337 lel, which has a 10.8-litre sixidered oil engine, the gross power iut of which is 190 b.h.p., developed 1,200 r.p.m. The torque output is lb.-ft., produced at 1,300 r.p.m., and drive is taken through a five-speed hromesh gearbox to the new twoid axle. This axle, as used in the 337 models, has ratios of 4.88 and 6.88 to 1, the reduction being obtained through epicyciic gearing. The change is effected by air pressure. The axle is available also with an air-operated differential lock which incorporates a free wheel. Airhydraulic braking is employed.
The chassis-frame side members have a maximum depth of 9.8 in. In its semi-forward-control version, the 337 chassis has a new cab with a full-width alligator-type bonnet opening through 90° and a small internal engine cowl. A wide onepiece curved windscreen and a large door opening ease the driver's work.
A basically similar cab is employed on the forward-control model, and further standardization between the two types has been achieved by using a similar radiator grille (which incorporates the headlamps). The 337 chassis, complete with forward-control cab, has a kerb weight of 4 tons and the vehicle can be used in conjunction with a 12-ton drawbar trailer.
This chassis is available also in a 4 x 4 version and the transfer box incorporates a free-wheel front-axle drive, which ensures automatic take-up of drive at the front wheels if the rear wheels start to slip. In this way, excessive fronttyre wear is avoided when the vehicle is travelling normally, but additional traction on the front wheels is always available when bad conditions demand it_
The second new model is the 327, which has been developed for export and differs primarily from the 337 in having a 120 b.h.p. oil engine. This 5.1-litre engine is noticeably shorter than the 10.8-litre unit.
As standard, the 327 has a single-speed axle with a ratio of 8.17 to 1, but the two-speed unit used on the 337 can be supplied, and the differential lock can be fitted.
Smallest model in the new series is the 322 10+-ton-gross chassis, which, like the 337 and 327, is available in semiforwardand forward-control versions. The 322 has a similar engine to the 327
and an identical five-speed synchromesh gearbox is employed. Gross train weight rating is 18.3 tons and the standard rearaxle ratio is 6.857 to 1. The two-speed axle is not offered. A 4 x 4 is available, with a similar type of transfer box to that employed in the 337_
Overall fuel economy, driving comfort and good gradient ability have been the main objectives in designing the new models. Most of them are capable, when running solo, of surmounting gradients steeper than I in 3, or 1 in 5 with a trailer. Alternative two-speed axle ratios are available on the 337 chassis, these being 4.11 and 5.77 to 1, and 5.63 and 7.9 to 1.
The 327 chassis, when fitted with a two-speed axle, have final-drive ratios of 7.17 and 10 to 1. The single-speed axle is optional on the 337 models.