Studies on the Efficient Utilization of Agricultural Machinery (3)

Analysis of the Economical Service Life of Combines

Abstract

The auther has investigated the method which decides the economical service life of combine N_{0 best}, and calculated the values of No best under various conditions.
(1) The auther considered that the coefficient of the total expense of repairs ∑r was an exponential function of double correlation between a number of years N, and the total of used area ∑A. From this, the yearly average expense of repairs during the service life R was calculated.
(2) The coefficient of average times for complete equipment t, and that of average expense of repairs r, could be considered to be under primary interrelations. The yearly average loss and gain of times to complete equipment S, may be calculated from this.
(3) By using R and S, the calculating formula of yearly expenses of use Y_(N) which was related to a number of years N and that of the economical service life N_{0 best} could be determined.
(4) When the coefficient of actual purchase expenses, g and A were 0 5, g₀ and 30ha, respectively, the N_{0 best} was equal to 9.4 years.