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Automation of tractor units
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ABSTRACTS conditions and for deriving trailer load data from D.B. pull and rolling resistance. [N.I.A.E.] P. Koemler and others. An Electronic Device for the Accurate Measurement of Slip. A.T.Z., April, 1964, Vol. 67, No. 4, p 119-121; (in German). In motor vehicles, the elastic deformation of the wheels makes it necessary to consider slip continually both during travel and during braking. It is given by the expression As/s o, where As is the difference between slip-flee distance travelled, so, and distance actually travelled. During motion and braking, slip increases with driving or braking torque. These torques reach their peak before deformation slip changes into local slip. Since coefficient of adhesion between tyre and road is determined by the relationship between force at the wheel circumference and wheel load, circumferential force must be measured as a function of slip in order to obtain the maximum possible coefficient of adhesion. Modern electronics offers an improved method which greatly reduces the errors inherent in earlier methods. The circumference of a disc (360 deg.) with as high a number of pulses as possible is continuously scanned. Part of the series of pulses as a function of the rotation of the control disc is stored in a counter. In the original version, the pulse disc has 100 slots uniformly distributed around the circumference; the control disc has a single slot extending over an angle of 240 deg. With synchronous running, 66-6 pulses are allotted over 240 deg. and are stored in the counter whereby the standard of comparison, 0 per cent slip, is given. With a difference in r.p.m., a faster-turning pulse disc produces more than 66"6 pulses in the store, and a more slowly rotating pulse disc fewer than 66"6 pulses. During the remaining 120 deg. of the control disc, the count is held by means of a gating circuit and passed to the attached high-speed recorder. An error of + 1 pulse (1 per cent) is reduced, in an improved version with a pulse disc producing 1000 pulses, to 1/1000. Features of the electric circuits are described. The device weighs 11 kg and is supplied by a 12-V battery. [M.I.R.A.] A . B . Kogauov. [Automation of tractor units]. Trakt. Selkhozmash., 1960, 30 (5) 13-14; illus. (R.). The working rates are calculated for a semi-automatic system giving duplicate control of steering and work by cable from one tractor to another, and another exercising group control of tractors on the straight, two tractor drivers turning the tractors at the headlands. [N.I.A.E.] R . J . Krizek. Approximation for Terzaghi's Bearing Capacity Factors." J. Soil Mech. Foundations Divn, ASCE, 91, No. SM2, Proc. Paper 4247, March, 1965, pp. 1-3. Using the general shear failure criterion, the ultimate bearing capacity of a shallow footing was expressed by Terzaghi in terms of l:earing capacity factors N c, NQ, N v. These factors depend only on the soil friction angle, d~, and are usually presented in graphical form. By means of an empirical approximation for each of these factors, a relatively simple equation is developed whereby the ultimate bearing capacity of a shallow footing can be determined directly without recourse to supplementary graphs. [A.S.C.E. Jour. Soil Mech. Div.] A . T . Lebedev, G. V. Lebedimkii and I. N. Serebryakov. [Automation of operation of hydrostatic tractors]. Trakt. Selkhozmash., 1964, 34 (9) 1-3; bibl. 3, illus. (R.). The automatic control system used with the hydrostatic transmission incorporated a control unit for engine loads of 95-100 per cent and one each for underload and overload conditions. Control unit parameters for 16, 100 and 200 h.p. tractors were studied with the aid of an electronic model which simulated the dynamic processes in the tractor control system. [N.I.A.E.] C . V . Malcolm. A penetrometer for detecting soil compaction. Aust. J. expl Agric. Anita. Hush., 1964, 4 (13) 189-190; bibl. 5, illus. The penetrometer has a tripod supporting a vertical shaft on which a hammer slides and is released at the top to drive a bullet-shaped anvil into the ground. The drop can be varied by altering the position of the upper stop or changing the weight of the hammer. A crayon attached to the top of the shaft is flicked against a strip of graph paper pinned to the wooden backing to mark the penetration after each hammer drop. [N.I.A.E.] S. Maauda and T. Tanaka. [Tractive performances of wheel type tractor. V: Research on the soil deformation by the tractor wheel and sinkage of the wheel lug in the soil]. J. Soc. agric. Much., Japan, 1964, 26 (1) 5-8; bil:l. 10, illus. (J.e.). Performance of skeleton wheels on soft paddy fields. [N.I.A.E.] S. ~ and T. Tanaka. [Tractive performances of wheel-type tractor. VI : Theoretical analysis of the stress distribution on the lug surface by the soil]. J. Soe. agric. Much. Japan, 1964, 26 (I) 9-13; bibl. 2, illus. (J.e.).
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62.
63.
64.
65.
66.
67.
ABSTRACTS conditions and for deriving trailer load data from D.B. pull and rolling resistance. [N.I.A.E.] P. Koemler and others. An Electronic Device for the Accurate Measurement of Slip. A.T.Z., April, 1964, Vol. 67, No. 4, p 119-121; (in German). In motor vehicles, the elastic deformation of the wheels makes it necessary to consider slip continually both during travel and during braking. It is given by the expression As/s o, where As is the difference between slip-flee distance travelled, so, and distance actually travelled. During motion and braking, slip increases with driving or braking torque. These torques reach their peak before deformation slip changes into local slip. Since coefficient of adhesion between tyre and road is determined by the relationship between force at the wheel circumference and wheel load, circumferential force must be measured as a function of slip in order to obtain the maximum possible coefficient of adhesion. Modern electronics offers an improved method which greatly reduces the errors inherent in earlier methods. The circumference of a disc (360 deg.) with as high a number of pulses as possible is continuously scanned. Part of the series of pulses as a function of the rotation of the control disc is stored in a counter. In the original version, the pulse disc has 100 slots uniformly distributed around the circumference; the control disc has a single slot extending over an angle of 240 deg. With synchronous running, 66-6 pulses are allotted over 240 deg. and are stored in the counter whereby the standard of comparison, 0 per cent slip, is given. With a difference in r.p.m., a faster-turning pulse disc produces more than 66"6 pulses in the store, and a more slowly rotating pulse disc fewer than 66"6 pulses. During the remaining 120 deg. of the control disc, the count is held by means of a gating circuit and passed to the attached high-speed recorder. An error of + 1 pulse (1 per cent) is reduced, in an improved version with a pulse disc producing 1000 pulses, to 1/1000. Features of the electric circuits are described. The device weighs 11 kg and is supplied by a 12-V battery. [M.I.R.A.] A . B . Kogauov. [Automation of tractor units]. Trakt. Selkhozmash., 1960, 30 (5) 13-14; illus. (R.). The working rates are calculated for a semi-automatic system giving duplicate control of steering and work by cable from one tractor to another, and another exercising group control of tractors on the straight, two tractor drivers turning the tractors at the headlands. [N.I.A.E.] R . J . Krizek. Approximation for Terzaghi's Bearing Capacity Factors." J. Soil Mech. Foundations Divn, ASCE, 91, No. SM2, Proc. Paper 4247, March, 1965, pp. 1-3. Using the general shear failure criterion, the ultimate bearing capacity of a shallow footing was expressed by Terzaghi in terms of l:earing capacity factors N c, NQ, N v. These factors depend only on the soil friction angle, d~, and are usually presented in graphical form. By means of an empirical approximation for each of these factors, a relatively simple equation is developed whereby the ultimate bearing capacity of a shallow footing can be determined directly without recourse to supplementary graphs. [A.S.C.E. Jour. Soil Mech. Div.] A . T . Lebedev, G. V. Lebedimkii and I. N. Serebryakov. [Automation of operation of hydrostatic tractors]. Trakt. Selkhozmash., 1964, 34 (9) 1-3; bibl. 3, illus. (R.). The automatic control system used with the hydrostatic transmission incorporated a control unit for engine loads of 95-100 per cent and one each for underload and overload conditions. Control unit parameters for 16, 100 and 200 h.p. tractors were studied with the aid of an electronic model which simulated the dynamic processes in the tractor control system. [N.I.A.E.] C . V . Malcolm. A penetrometer for detecting soil compaction. Aust. J. expl Agric. Anita. Hush., 1964, 4 (13) 189-190; bibl. 5, illus. The penetrometer has a tripod supporting a vertical shaft on which a hammer slides and is released at the top to drive a bullet-shaped anvil into the ground. The drop can be varied by altering the position of the upper stop or changing the weight of the hammer. A crayon attached to the top of the shaft is flicked against a strip of graph paper pinned to the wooden backing to mark the penetration after each hammer drop. [N.I.A.E.] S. Maauda and T. Tanaka. [Tractive performances of wheel type tractor. V: Research on the soil deformation by the tractor wheel and sinkage of the wheel lug in the soil]. J. Soc. agric. Much., Japan, 1964, 26 (1) 5-8; bil:l. 10, illus. (J.e.). Performance of skeleton wheels on soft paddy fields. [N.I.A.E.] S. ~ and T. Tanaka. [Tractive performances of wheel-type tractor. VI : Theoretical analysis of the stress distribution on the lug surface by the soil]. J. Soe. agric. Much. Japan, 1964, 26 (I) 9-13; bibl. 2, illus. (J.e.).