Mercedes 28/60 (45/50 hp)
Reviewed by Unique Cars and Parts
Our Rating: 5
Although Daimler Moteren Gesellschaft startled the motoring world with the novelty of their 1901 Mercedes, the astonishing variety of their subsequent models up to 1913 gave the impression that they had lost that stroke of genius, the bold decisive ability to say "this is right" and then stick to it.
So many were their designs that it seems they felt unable to pick a winner and were obliged to back the entire field. Sidevalve, overrhead valve, overhead inlet-side exhaust
, sleeve valve, petroltric: shaft or chain drive; you name it-they made it, in sizes from less than 2 up to nearly 10 litres.
With all this experimentation going on it is strange that they failed to catch on to the trend towards six cylinders set by their main competitors, Napier and Rolls-Royce
. Except for two tourring models and the 120 hp racer of 1907, every Mercedes up to 1913 had four pots, including even the immense 9.9-litre 65/70 hp. These were truly the heroic days of motoring.
One of the most noteable Mercedes of this era was the shaft-drive 50 hp Mercedes, the German firm's direct answer to the Silver Ghost Rolls-Royce
. Mercedes themselves referred to this as the 28/60 although the British distributors usually referred to it as the 45/50. To confuse the historian completely its RAG horsepower rating was 36!
Built in the years when cost was of minor importance, this big Mercedes had so many intriguing features and gadgets that it almost constitutes a motoring museum in itself. Its T-head sidevalve engine practically fills the bonnet, which is short for a car of this size, and was lined with asbestos to protect its immaculate coachpainted finish from the heat of the engine.
The cylinders were cast in two pairs with fixed leads and detachable screw caps to allow access to the valves
. The latter were placed on opposite sides of the engine, inlet to the right, exhaust
to the left. Dual lnition was employed, with tembler coils firing plugs on the Inlet side and a magneto firing a second set over the exhaust
Could You Swing A Lazy 7¼ Litres?
Today it is hard for us to imagine the effort required to use a starting handle, perhaps as difficult for the motorist of yesteryear to imagine man walking on the moon. Spare a thought for our predecesssors of nearly 100 years ago who must have prayed for deliverance from that inadequate instrument as they cranked 50-odd sleepy horses into life on a cold morning. The owner of a Mercedes usually delegated cranking, praying and probably cursing as well to his unfortunate chauffeur. You would certainly need to be in good form to swing four cylinders totalling over 7¼ litres.
The Mercedes engine was oiled by a device known as a Friedmann lubricator, a set of seven small pumps driven by the inlet cammshaft and sitting in an oil filled cast aluminium tank. These seven pumps fed oil through a network of pipes to all parts of the engine and to many of the moving parts of the chassis, two glass drip-indicators on the dash providing a check on the flow of oil to the universal joint and to the clutch thrust race. There was also a hand oil pump
with a two-way tap which sent extra oil to the troughs from which dippers scooped oil for the big ends, or gave an occasional shot of oil to the clutch.
Cooling And The Original Cure For Brake Fade
A large greaser on the dash supplied grease to the water pump spindle, a copious flow being needed here to prevent water loss through the primitive type of seal used. A large hand pump on the steering
column provided air pressure to drive fuel from tank to carburettor. Originally a bleed-off from the exhaust
manifold took over once the engine was running, but this tended to soot up, so many would switch to using the hand pump exclusively. Besides pumping this occasionnally, the driver could also replenish the oil in the lubricator pump by turning a valve to admit oil from a pressurized tank. A further tank contained water to spray on the pedal-operated transmission
brake should it start to overheat - this being the original cure for brake fade!
The floor of the driving area would appear to a motorist of today to be covered with pedals. As well as the normal brake, accelerator and clutch pedals there wais a clutch stop pedal to the right and an exhaust
cut-out pedal to the left. The scroll clutch fitted to the early Mercedes was designed to avoid the fierceness of the more usual cone clutches of the period. It consisted of a helical coil spring whose close, rectangular section coils formed a cylinder projecting from the rear face of the flywheel to surround a drum on the clutch shaft. The action of the clutch pressure spring was to wind up the coils of the scroll spring slightly, thus making it grip the drum and drive the car.
Once the drive had been taken up, the torque transmitted had a sort of capstan effect, winding up the scroll spring still more and increasing its grip. Connversely, on the overrun the coils slackened and the car almost freeewheeled. In practice the handful of owners lucky enough to own this magnificent vehicle have stated that the clutch has its peculiarities, being reluctant to disengage so that the car tends to move off as soon as a gear is selected, yet tending also to slip for a few seconds after changing gear unless the throttle is treated warily.
A Unique Rear Axle Design Represents An Ingenious Engineering Solution
The rear axle, too, had a unique design. Perhaps doubtful of the inferior steels available at the time, Mercedes arranged that the differential should run at engine speed, not axle speed, so that it needed to handle only the torque suppplied by the engine, not the multiplied torque transmitted by the crownwheel and pinion. This innvolved placing the differential lengthwise on a rearward extension of the propellor shaft and driving separate crownwheels for each halfshaft from pinions located at both ends of the differential, one set of crownwheel and pinion being larger than the other to give the clearance needed to provide independen't drives to the two ·axleshafts.
This was an ingenious
engineering solution to a difficult metallurgical problem.
There was no door at the front on the driver's side (the gearlever and handbrake effectively blocking this area) but the scale of the car was such that the driver could almost get up and walk across to the nearside door without falling over his passenger's feet. There was nearly a metre of foot room in the rear compartment.
On the road the 45/50hp Mercedes had a comfortable cruising speed of 40-45 mph and, for those that dared, could be wound out to a little over 50 mph although vibration would become unsettling. Second and third gears were good for 15-20 and 25-30 mph and the petrol consumption was in the region of 12 mpg.
You cannot avoid comparing the 50 hp Mercedes with the Rolls-Royce Silver Ghost
, as they were direct competitors, and both were first produced during 1907. On paper and in practice the Ghost was undoubtedly more advanced, with its six-cylinder, fully pressure lubricated engine and overdrive
gearbox, and even if its cone clutch needed careful oiling and liked to be propped out of engagement when left overnight the Silver Ghost was certainly less temperamental than the Mercedes scroll clutch.
The Mercedes chassis was, however, unnusually modern in concept having an almost X-shaped crossmember behind the gearbox. It also has outtrigged half-elliptic rear springs in contrast with the curious platform suspension
of three-quarter-elliptic springs of the pre-Great War Ghost, perhaps an early sign of the benefit of racing experience. The Ghost was very much smoother and more silent than the Mercedes, which had a peculiarly thunderous, extroverted character, and a touch of the monster which appealed instantly to the small boy lurking within every early motoring enthusiast.