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Assuming the tractor is equiped with a three-shank ripper, allowance must be made in this item for the cost of tips, shanks and shank protectors. Bank gravel will be loosened by the ripper as part of the production dozing application.
Assume your knowledge of tile operation indicates the ripper will be used only about 20;s of total tractor operating time. Estimated tip life while in L se is 30 hours. Therefore, tips will be replaced: 30 Hours
= each 150 hours of tractor operation .20 Shank protector life is estimated at three times tip life or 450 hours of tractor operation. In this medium duty application, no shank replacement is expected in the 10,000 hour depreciation period of the tra, tor.
Using local prices for these items, hourly costs are estimated as follows:
Items 3, 4, 5, 6 and 7 can now be added and the result, $6.98, entered in space (N), Total Operating Costs. Operator's Hourly Wage
Assume this is $6.00 including fringe benefits. This figure is entered in space (P).
Total Owning Costs, Total Operating costs and Operator's Hourly Wage are now added together and the result, $20.71, is entered in space (Q). The itemized estimate of Hourly Owning and Operating Costs is now complete.
10,6 5.9 760 6.6 11.2 765 766 8.3 408 2.0.6
6.0 Gold 902 10.6 206 5.8 5.5 1103 70? 8.0 769 4.8 10044
Source: Construction Equipment Magazine, 1963 survey.
employed manufacturer designations of overall tire quality (premium, first line, service line) mean
very little since universally defined standardized
designations do not exist.
The one tire type which has shown itself clearly superior to others, (both in terms of tread wear
and its ability to withstand damage) is the radial.
At present, these tires represent only a relatively
small fraction of the total tire market, as shown
Their tread life is nearly twice that of bias ply
tires and about 60 percent greater than that of
belted bias tires.*
Within the various tire categories, there is con
siderable variation in tread life.
Based on U.S. Department of Transportation tests. Consumers Union testing showed tread life ranging from 15,000 miles to 50,000 miles, more than a three fold difference from lowest to highest (Consumers Reports, August 1971).
factors include the type of car driven, the extent
to which wheel alignment and balance are maintained, driving habits, tire pressure, road surface and con
ditions, climate and the specific manufacturing comp
Based on testing of the three types of tires, radial
tires were also shown to be superior in terms of per
formance and rupture resistance. Tests were conducted by driving the tires over protruding spikes with rounded ends. Both worn and unworn radials outperformed the
other types. Bias ply tires tested as the weakest
and belted bias were intermediate. Consumers Union
also tested the stress resulting from high speed operation. Belted bias tires suffered a high failure rate,
thus indicating that these tires were not capable of withstanding extreme overload, under inflation or sustained high speed. The radial and bias ply tires were approximately equal in respect to these characteristics. The apparent superiority of radial tires, however, has not resulted in their wider adoption by the public (i.e.,
radials only account for 13 percent of the market). The
reasons for this are as follows:
a. There is a scarcity of radial tires in the
United States because most American manufacturers
d. The initial cost of radials is higher than that
of other types. For example, the average price
for conventional tires is between $25 and $30
each. In spite of this higher initial cost,
on a per mile basis radials show a cost of approxi
mately 1 cent while others with lower initial
price, cost 3,4 cents per mile.