Twin-steer Tractive Unit and Nei lids from Daimler-Benz
Page 58
Page 59
If you've noticed an error in this article please click here to report it so we can fix it.
By A.J.P. WILDING
AMI Mech E, MI RTE
NEW goods vehicle designs which Daimler-Benz AG, is to feature at the forthcoming Frankfurt Show were unveiled to the European technical Press last week at the Hocicenheim car-racing circuit in Germany. Five new models have been introduced—a three-axle tractive unit for use at 38 tons g.t.w., four-wheelers for gross weights of 8, 10 and 12 tons when operated solo which are additional to the existing Mercedes-Benz range, and a fourwheeler for operating at 14 tons gross solo which replaces the previous model for this weight. The same style of forward-control cab is used on all five chassis, that on the three-axle machine (the LPS 2020) being the same as the unit used on the LP 1620 which was featured at last year's Commercial Motor Show, whilst the others—the LP 810, 1013, 1213 and 1418—have a slightly modified version of it.
The main differences between this new cab and the earlier forwardcontrol design used on Mercedes-Benz vehicles and retained for existing models which continue in production, are that increased forward visibility is given and the front panels are flat, not slightly curved; the engine is located below the floor line, and improved driver comfort is given.
Apart from the fitting of the new cab, the LP 1418 has had a number of changes in mechanical specification. This is a particularly interesting model from a British point of view as the tractive-unit version, the LPS 1418, is said to be a "best seller" by Normand Ltd., Mercedes-Benz concessionaires for the UK. This model is sold here for operation at 30 tons g.t.w., but it is reported that the new design LPS 1418 will not be available with right-hand steering until the middle of 1966 and the retail price will be increased by some £800. The existing design will continue to be available.
The most important of the new models in Germany will be the LPS 2020 in view of the recent increase in maximum permissible weight limits c22 there which allow for 38-ton g.t.w. artics. As the maximum axle load possible is still 10 tons, this means that to gross 38 tons on a four-axle outfit would involve an 8-ton front axle loading.
Apart from the difficulty of designing a steering axle for this capacity the length of tractive-unit and position of fifth wheel which would have to be provided make this totally impracticable. The additional axle on the LPS 2020 is steered, has single tyres and is located close to the driving axle. The general layout is similar to that of the Scammell Trunker which was introduced recently, although there are said to have been similar designs produced by Daimler-Benz before.
The engine used in the LPS 2020 is the OM 346, which gives a maximum net output of 210 b.h.p. DIN at 2,200 r.p.m. and the gearbox is a ZF AK 6/80 constant-mesh unit which can have a splitter unit to give 11 effective forward ratios instead of the standard six.
It will be seen from the accompanying diagram what the axle loadings must be for an artic incorporating the LPS 2020, and to get the 9.5 tons on each of the semi-trailer axles the centre spacing has to be 2 m. (6 ft. 6-7 in.). In this way the axles count as single units and are not limited to 16 tons, which is the German limit for bogies.
At Hockenheim an LPS 2020 was shown coupled to a new design Schenck semi-trailer with this axle spacing and an interesting feature was that both axles were steered by a linkage to the rear cross-member of the tractive unit. Apart from reducing tyre wear on a bogie with such an axle spacing the steering of the axles made a tremendous improvement in manceuvrability.
Test runs were given of all the new models and 1 was able to follow behind the LPS 2020 outfit as well as to drive it. Although the overall length was 15 m. (49 ft. 2.5 in.) sharp turns which would have been almost ossible even for a normal-length six-wheeler were negotiated withdifficulty. The way in which the i-trailer axles kept very nearly to same tracks made by the tractive was surprising, 'riving an outfit of this length with semi-trailer axles would have 1 a very difficult task, particularly was on the wrong side of the road the wrong side of the cab to the But I found no difficulty at with this outfit and no need to go over to the opposite side of the I to get round turns. I found the 12020 a very pleasant and cornable vehicle to drive, with adeLe power—there were no hills, but Aeration performance appeared onable—light steering and responand powerful brakes.
here is considerable support on Continent for increasing permis: axle loads to 13 tons, and whilst LPS 2020 allows for 38 tons g,t.w. rout the need to go to the expense weight of an extra driving axle it ns to be asking a lot for an axle only 10 tons on it to move 38
This may lead to traction dif
ficulties in bad conditions, but this could not be checked.
Turning to the other new MercedesBenz models, each of them is made in various wheelbases and in rigid or tractive-unit versions. The LP 810 is also available as a bus chassis and for export the normal gross weight rating is increased to nine tons. The engine used is the OM 352, with a maximum net output of 100 b.h.p. DIN at 2,900 r.p.m., and braking is by an airassisted hydraulic system.
The LP 1013 is a larger version of the LP 810 and has similar technical features, but the OM 352 engine develops a maximum of 130 b.h.p. DIN at 2,800 r.p.m. Instead of a standard recirculating-ball steering unit (also on the LP 810) a ZF hydraulicralwer-steerine system can be provided. The new LP 1213 also has the 130 b.h.p. net engine and represents a link between the 1013 and the earlier 1113, which have gloss weight ratings of 10.5 tons, and the LP 1413 which has a total permissible weight of 14 tons. The general design of the LP 81(1, 1013 and 1213 are the same except that the chassis and units are
(Above) One of the interesting exhibits, apart from the new models, was an LK 1413 chassis fitted with an OM 352,4 turbocharged diesel.
strengthened where necessary to cater for the different weight ratings. Whilst the 1213 has the same engine as the 1013 at present it is reported that a 130 b.h.p. DIN power unit will be available in about six months' time.
The LP 1418 which, as already stated. is also offered as a tractive unit for 30 tons gross, has a solo gross limit of 14 tons. This model has an OM 346 engine which develops 180 b.h.p. DIN -(net) and is equipped as standard with a two-speed driving axle, ZF hydraulic steering, two-stage springs at the front axle and threestage at the rear and dampers all round. Braking is by a split-circuit, air-pressure-assisted hydraulic system.
A full range of Mercedes-Benz semi-forward-control models was also .displayed at Hockenheim. Amongst these was an LK 1413 fitted with an OM 352A engine which is turbocharged and produces 150 b.h.p. net. The use of turhocharging on the OM 352 engine is a new development byDaimler-Benz.