1935-01-01

Vehicle Design from a Maintenance and Operating Standpoint 350090

THE Subcommittee on Motor-Vehicle Design from the operation and maintenance standpoint was instructed to continue its studies and prepare a short summary for the 1935 Annual Meeting.
In discussing the possible subject matter with the Committee, so many phases of this subject were questioned that it was impossible in a short space of time to give them full consideration in time for this presentation. I have therefore limited the report to cover mainly the electrical group and the highly controversial subject of motor-truck ratings.
The largest number of complaints and the most severe criticisms on the electrical group come from fleet operators in the so-called low-temperature area. Winter starting-difficulties are prevalent, not only on account of inadequate storage batteries and starting motors but inefficient generators as well. Likewise, this problem is all tied in with the much discussed problem of winter grades of crankcase lubricating oil.
I have not attempted to define where the starter-battery difficulty stops and the lubrication problem begins. However, I am of the opinion that if engine design were improved to the point where 20-W oils could be used economically in all makes of motor-vehicles, our winter starting-difficulties would be minimized.
I have set up data showing the inconsistency that exists between the generator-battery starter-combination as applied by various manufacturers. It is obvious that the winter starting-requirements are not generally known. It is the general feeling among the operators that this subject is of sufficient importance to warrant special treatment on the part of the manufacturers.
Motor-truck ratings have been discussed pro and con over a period of years with nothing tangible developed that the operator could use as a guide in the purchase of motor vehicles for a definite transportation job. I have attempted to correlate sufficient data furnished by the manufacturers and, using their own advertised ratings, to show first the lack of consistency and second the lack of standardization.
The method used in developing this practical rating is simply taking the manufacturer's advertised gross vehicle weight with his advertised standard axle ratio, equipping that vehicle with sufficient tire size to comply with the Rubber Association's rating for the particular gross vehicle weight and for the performance factor, and computing the grade ability at 20 m.p.h.
As a check on the strength of the component units in the vehicle, the front-axle-knuckle diameter at the inside bearing, the rear axle, outside tube diameter full-floating type, section modulus of frame, clutch area, effective braking area, and engine displacement, all computed in terms of 1000 lb. of gross vehicle weight, maximums, minimums and averages have been set up for all classes of vehicles.
To the operator, it is intended as a guide to rate a vehicle for a specific job. To the manufacturer, we trust it will be used for the production of a better-balanced vehicle.

SAE MOBILUS

Subscribers can view annotate, and download all of SAE's content. Learn More »

Access SAE MOBILUS »

Members save up to 43% off list price.
Login to see discount.
Special Offer: With TechSelect, you decide what SAE Technical Papers you need, when you need them, and how much you want to pay.
X