Conceptual approach to select parameters of hydrostatic and mechanical transmissions for wheel tractors designed for agricultural operations

Abstract

As a result of theoretical and experimental efforts, innovative scientifically grounded conceptual approach to select hydrostatic and mechanical transmissions (HMT) for wheel tractors designed for agricultural operations has been proposed. The approach is characterized by focusing on kinematic parameters, power parameters, and energy parameters of the transmission while performing technological operation "plowing"; it also takes into consideration braking features of a tractor in the context of various braking types. Application of the approach offers an opportunity to improve technical level of transmissions while updating current wheel tractors and designing new ones; moreover, that will better controllability as well as braking efficiency. The conceptual approach developed on the basis of proposed techniques and applied mathematical models makes possible to determine rational structure and basic design parameters of two-flow HMTs while designing; it also helps formulate recommendations concerning a technique for service braking and emergency braking under specific operational conditions.

Comparative analysis of transmissions of mine diesel ­locomotives with different component schemes

“…Relating to HMT 2, recommended area of clutch arrange ment determined by paper [19] coincides completely with rec ommendations in paper [6]; that is, in the context of HMT with output differential (HMT 2) it is more preferable to ar range the clutch within the hydraulic branch of the closed cir cuit behind the HD.…”

“…Thus, equation one explains the transmissionengine rela tion as follows Power transmission parameters can be described using the following equations where w i is the angular velocity of transmission segment; w d is the angular velocity of engine crankshaft; i j is transmission ra tio; k is internal drive ratio of planetary gear set; e 1 , e 2 are pa rameters to control HD hydraulic machines; q 1 , q 2 are maxi mum efficiency of hydraulic machines; γ is the coefficient characterizing power flow direction (γ = 1 is straight power flow; γ = -1 is reverse power flow); DQ is hydraulic liquid leak age in all hydraulic machines involving symbol of pressure dif ference in HD; DP is working pressure difference in HD; V aa * 0 is the volume of liquid being compressed; E( g * ) is module of working liquid tension depending on gas content percentage g * ; w 02 , w 00 are angular velocities of hydraulic pump shaft (w 02 corresponds to the input differential HMT scheme; w 00 corre sponds to the output differential HMT scheme) calculated in the process of iteration solution of nonlinear matrix system during previous iteration being considered as that equal to 0 for iteration one; w 03 , w 01 are angular velocities of hydraulic motor shaft (w 03 corresponds to the input differential HMT scheme; w 01 corresponds to the output differential HMT scheme) cal culated in the process of iteration solution of the nonlinear matrix system during previous iteration being considered as that equal to 0 for iteration one; K iy , C iy are coefficients of loss es for the hydraulic pump (i = 1) and hydraulic motor (i = 2); m is the coefficient of dynamic viscosity; Y is the coefficient characterizing the range of motion (Y = 1 is traction range, Y = 0 is transport range); M nm are moments within HMT com ponents; m are indices corresponding to the number of angular velocity of the component; n are indicesletters corresponding to moments at the ends of the components; n j is efficiency of the gear; Q is the coefficient considering losses within gear clutches (Q = 0 is the coefficient ignoring losses; Q = -1 is the coefficient considering the losses); N nm is power transmitted by HMT components; h 13 , h 23 are efficiencies within sunpinion and epicycleplanet gear clutches when the carrier is stopped determining losses of moments; DM 1 , DM 2 are losses of a mo ment within hydraulic machines [6]; 1 2 8 , ,..., K K K are coeffi cients of hydromechanical losses; D qi is typical dimension of hydraulic machines; DP 0 is working pressure difference within HD calculated in the process of iteration solution of the non linear matrix system during previous iteration being consid ered as that equal to 0 for iteration one; G is weight of a mine diesel locomotive; r is the radius of wheels; f is resistance to the motion coefficient.…”

“…However, acceleration of mine trains driven by diesel locomotives aggravates a problem of safety in terms of braking mode. Therefore, it involves the necessity to upgrade available transmissions and develop advanced ones for home diesel lo comotives basing upon progress of computation and theoreti cal techniques to analyze "enginetransmissiondiesel loco motive" system in terms of braking mode [6].…”

“…Paper [19] does not indicate area of power flow break with in the close circuit of HMT 1; that is clutch area is not speci fied. Paper [6] has identified the fact that from the viewpoint of braking process dynamics, in the context of HMTs operating according to input differential scheme, it is recommended to arrange the clutch either behind the engine or within the hy draulic branch of the closed circuit in front of HD (no alterna tive is preferable). Consider a case when the clutch is arranged within the hydraulic branch of the close circuit in front of HD as a part of analysis of braking process of a mine diesel loco motive with HMT 1.…”

Model of surface roughness in turning of shafts of traction motors of electric carst

“…Research is also relevant for shafts of vehicles with hydro mechanical gears [16,17]. In terms of the vehicle flow distri bution the optimal machine parts' lifetime can be calculated.…”