ast mover, and seller
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Good journey times, driver comfort and a considerable carrying capacity are the hall marks of Mercedes-Benz's 1617, as Bryan Jarvis found on our Welsh testing route
TWO-AXLED rigid vehicles designed for operation at 16.26 tonnes gross vehicle weight have for many years been intercity workhorses on the multidrop network and are likely to remain so for many more. Most manufacturers, recognising this, offer a range of wheelbase options to help fleet operators in selecting the type and length of body they need.
Mercedes-Benz (UK) markets a choice of four at 16 tons: a 3.9m (154in) which is suitable for tipping work, and 4.5, 5.2 and 5.9m (177, 205 and 232in) for other types of haulage.
It was the longest of the group, fitted with a 7.3m (24ft) platform body which Mercedes chose to offer CM for testing around our Welsh route.
We had tested this model previously in a 16-ton group test (CM March 8, 1980) in the company of seven other vehicles, all from the major manufacturers and all having flat or dropside bodies. Unfortunately, at that time, Mercedes could only supply the vehicle with a box body, which left a small cloud of uncertainty over the results of that test. To complicate matters further, it also had a cab-roof air deflector fitted.
Returning 18.5 lit/100km (11.5mpg), it had in fact beaten all for economy except the Magirus Deutz (20 lit/100km 12.47mpg) and the Dodge G16 (18.8 lit/100km 11.7mpg), while returning the highest overall average speed of 61.3km/h (38.1mph).
Not surprisingly, there have been no drive-line changes between that vehicle and the one I tested. It still has the familiar Mercedes 0M352A 124kW (168bhp) turbocharged engine driving through the eight-speed range-change gearbox to the 5.22 to 1 final drive.
It might seem unusual that this manufacturer's high-revving engine produces maximum power at 2,800rpm when other manufacturers are obtaining similar outputs at lower engine speeds of around 2,400rpm and less.
Yet this characteristic ob viously suits the drive-line gearing, striking a nice balance between performance and fuel economy because the test vehicle returned a very respectable 24 lit/100km (11.75mpg) at an overall average speed of 60.3km/h (37.54mph).
As the comparison charts on page 31 show, both the Ford Cargo 1615 and Karrier Motors' Dodge RIG16 produced much better fuel economy with 21.6 lit/100km (13.08mpg) and 20.8 lit/100km (13.6mpg) respectively. A Volvo F16 tested in Picture above: The Mercedes 168hp turbocharged 0M352A engine strikes a fine balance between power and economy, returning 11.75mpg overall with high average speeds. August 1980 was also marginally better with 22.9 lit/100km (12.4mpg) and lveco's 159.17, tested in November last year, had an 24.3 lit/100km (11.6mpg) return.
One characteristic which many operators regard as all-important is the ability to maintain fast journey times and in this respect the 1617 did not disappoint. Only the Ford Cargo with an average speed of 62.4km/h (38.8mph), and more recently Bedford's TL1630 with 62.1km/h (38.6mph), have managed to outshine it.
Throughout the test earlymorning freezing fog lifted slightly as the day progressed. On the 52-mile stretch of the M4 between Membury services and Aust, visibility was not as bad as I had at first feared. There were no restrictions and I was able to maintain quite safely a high average speed of 92km/h (57.0mph). As my tachograph chart shows, I was quickly into eighth gear and maintained a near-maximum speed all the way to the Aust turn-off.
The rev counter is marked with a green sector to show the engine's most economical speed range between 1,400 and 2,40Orpm.
At 60mph the needle strayed beyond this to 2,500rpm, while at 40mph, also in top gear, it held near the centre of the "green" at 1,700rpm.
Fuel consumption over the A and B-class part of the route was very close to the motorway figure and this must be an indi ciation of the engine's flexibility. The hill climb beyond Mon mouth was cleared in a fast time; I needed to drop into sixth gear but did not fall below 40.2km/h (25mph). Road speed dropped very quickly on the steep one-inseven Wantage Hill and a slight hesitancy on the gear change when crossing into the low range probably caused it to drop into third gear when fourth might have been adequate.
The Mercedes eight-speed range-change box is standard on the three longer wheelbases, and with the 5.22 rear axle gives a maximum top speed of 103km/h (64mph), (Governor run-out allowed this to creep up to 108km/h (67mph) during the track testing.) The range-change operated very smoothly as befits a well run in demonstrator with 53,000km (33,000 miles) on the clock. Low-shift loads on the transmission made gear changing quite easy and the ever-present indicator lights on the dash told the driver which range was engaged.
Unfortunately, as early as the initial tests at Mira the clutch pedal remained depressed momentarily on two occasions, the second time while attempting to start on the one in four hill.
It had cleared the one in five with ease and but for the pedal sticking down it would, I believe, have taken off the steeper hill as well.
Towards the end of the Welsh route it had become troublesome particularly when trying to cross the busy A415 out of Oxford. Several opportunities arose to move out, but each time the pedal remained down. A well controlled nudge with the toeend stalled it first time, but on the second occasion I had its measure and made a slick crossing. As Wantage drew near I became slightly apprehensive, but it did not trouble me again during the test.
Mercedes-Benz assured me several days after the test that it had been nothing more than air in the hydraulic system and the clutch worked perfectly after had been bled. M-B (UK) also assured me that it is not a corn-mon fault and pointed out that Christian Salvesen operates 143 of them and have had no similar clutch problems.
One thing that I am sure their drivers do experience is the 1617's comfortable mediumsleeper cab and the vehicle's well controlled ride and its good handling.
Temperatures of —5 degrees C prevented me from using the ride and handling section at Mira and because the 1617 was specified with a normal unsprung seat I was wary from the start.
I need not have been because my seat was very comfortable, helped no doubt by the well suspen ded cab. Both day and sleeper cabs have a single trans verse leaf spring at the rear with two hydraulic dampers. At the front end, however, the sleeper version has two U-shaped springs with hydraulic dampers and a transversely mounted stabilised bar to minimise cab dip ping on twisting roads.
This system proved very effective on the journey between Witney and Abingdon on the A415, and 11-mile stretch that has all the ingredients bar tram lines for a ride and handling course.
Much of the credit for the well controlled ride over this difficult stretch must be given to the effectiveness of the large semielliptic leaf springs, double-acting hydraulic dampers and anti roll bars front and rear. The helper springs at the rear played their part too.
Mercedes now fits its own re circulating ball with integral power steering and it is quite effortless in use particularly during low-speed manoeuvring.
German law requires the fitting of large diameter steering wheels to allow the extra turning effort needed should the power assistance fail. This wheel was 546mm (21.5in) diameter and the column was adjustable for rake.
Its well-sprung cab is also a fairly quiet, draught-free environment for a driver to spend a working day in. At 40mph in top gear our noise meter recorded 70dB)A) while at 60mph it held at 75dB(A). Mercedes-Benz is not noted for building the lightest trucks and this one was no exception.
Its fairly high kerb weight brings the permissible payload down to 10.2 tonnes.
Using standard 11R 22.5 tyres on the front axle gives a frontaxle plated weight of 6,1 tonnes. M-B offers optional 12R 22.5 tyres, which raise this loading to a maximum of 6.6 tonnes to allow more flexibility with load distribution. The option costs an extra £126.
I was a little disappointed to see that our test vehicle did not have the heater/ventilator controls positioned alongside the in strument panel where the driver can reach them more readily. This, and a number of other specification changes, have been incorporated since the beginning of this year. The wash/ wipe feature is moved to the stalk-switch mounted on the steering column, and the park brake lever, presently located where the driver's left knee nor mally rests, is now repositioned to the right of the instrument panel near the grab handle. The engine's fixed cooling fan is replaced with a visco-type fan, and heated rear-view mirrors are an added option.
With these changes now included, a two or three-day trunking delivery run using this type of vehicle will become less of a strain for any driver.
Entry into the cab is very easy with well placed handles, a low bottom step and a wide doorway. Once seated, the deep windscreen and side windows offer wide clear views. Side deflectors mounted on the front corners proved to be very useful in keeping the door windows and driving mirrors clean during the damp, dirty weather that I encountered and the two large windscreen wipers were more than adequate.
Cross-cab access is reasonably unrestricted at present and with the repositioning of the park-brake lever it will improve.
The cut-away portion in the header rail console above the passenger seat allows sufficient height for an average-height person to change his clothes with the seat pushed forward and there are two storage spaces under the lower bunk.
Summary Although the Mercedes 1617 has a slightly lower payload capability at 10.28 tonnes than some of its rivals, the 5.9m (19.3ft) wheelbase model with a generously-sized sleeper cab will offer considerable carrying capacity when fitted with the largest permissible box body.
Compared with the E R F M1 6P2 it may seem overpowered, but the 1617 is well able to produce good journey times along motorway or urban routes without undue stress on either the engine or the transmission. It is very easy on the driver too.
Last year Mercedes managed to sell 970 of these units in an expanding market, traditionally dominated by Leyland, Ford and Redford, and judging by its performance it is quite capable of improving on this position still further.