Klymenko I. Substantiation of the rational braking methods for a mine diesel locomotive with hydrostatic-mechanical transmission

The thesis deals with the solution of a scientific and practical problem of providing the braking efficiency for mine diesel locomotives with hydrostatic-mechanical transmissions (HMT) and with the substantiation of rational methods for the braking process implementation. Possible ways of the improvements of locomotive transport at Ukrainian mines have been substantiated; the improvements are possible by using stepless hydrostatic-mechanical transmissions on transport means. To analyze dynamics of the acceleration and deceleration of diesel locomotives with stepless two-flow HMT, complex “plane” mathematical models have been applied as they help reveal quite accurately a physical nature of the processes and identify the HMT influence on the diesel locomotive dynamics in terms of the effect of comparatively minor lateral forces along with the minimal time consumption for the adaptation for specific operating conditions. A generalized mathematical model of braking process of a mine diesel locomotive with HMT has been developed, making it that possible to analyze certain changes in HMT kinematic and power parameters under different conditions of diesel locomotive operation. Braking process of a mine diesel locomotive has been modeled for a diesel locomotive with HMT with input differential and with HMT with output differential in terms of the motion within both traction and down-grade and up-grade transport range in terms of different initial braking velocity for the following braking methods: if there is the kinematic motor disconnection from wheels; at the expense of HMT and braking system in terms of the preserved kinematic motor connection with wheels; at the expense of HMT in terms of the preserved kinematic motor connection with wheels; and at the expense of a braking system in terms of the preserved kinematic motor connection with wheels. The operating HMT parameters obtained while modeling should not exceed critical values: maximum values of working pressure differences in HMT should not be more than the ones specified for hydraulic machines – 40.0, MPa; maximum values of angular velocities of the hydraulic pump shafts and hydraulic motor – 460.0 rad/s. The overall study of a braking process of a mine diesel locomotive has resulted in the following: from the viewpoint of braking in terms of 8 loaded cars and 50‰ descending, use of HMT #1 on diesel locomotives is not recommended as it is impossible to have deceleration for a mine locomotive without complete stop with the preserved transmission operability; use of HMT #2 on diesel locomotives is admissible in terms of the use of braking at the expense of a braking system in the context of kinematic motor disconnection from the driving wheels (for emergency braking with the complete diesel locomotive stop) or at the expense of HMT at the preserved kinematic motor-wheels connection (to reduce the motion speed). To solve a problem of searching for rational parameters of mine diesel locomotive transmissions, a software design methodology has been developed; the methodology has made it possible to determine the optimal number of gearwheel teeth by direct sorting out of all possible solutions.