© Strojni{ki vestnik 48(2002)8,459-466 © Journal of Mechanical Engineering 48(2002)8,459-466 ISSN 0039-2480 ISSN 0039-2480 UDK 629.367:531.232 UDC 629.367:531.232 Predhodna objava (1.03) Preliminary paper (1.03) Vpliv ra~unskega polmera obra~anja goseni~nega vozila na potrebno mo~ motorja pri obra~anju The Impact of a Fixed Kinematic Turning Radius of a Tracked Vehicle on the Engine Power required in a Turn Vjekoslav Stojkovi} - Dinko Mikuli} V prispevku je analiziran vpliv velikosti računskega polmera obračanja na potrebno moč motorja pri obračanju in na obremenjenost drsnih elementov mehanizma obračanja goseničnega vozila, ki ima mehanizem obračanja z več izračunanimi polmeri obračanja. Definirani so parametri, ki opisujejo relativno spremembo potrebne moči motorja pri obračanju, relativno spremembo zavorne moči na drsnih elementih mehanizma obračanja in spremembo koeficienta koristnega delovanja mehanizma obračanja v odvisnosti od relativnega polmera obračanja. Podana so priporočila za izbiranje računskih polmerov obračanja pri projektiranju mehanizma obračanja goseničnega vozila. © 2002 Strojniški vestnik. Vse pravice pridržane. (Ključne besede: goseničarji, obračanje vozil, moči motorjev, mehanizmi obračanja) This paper analyzes the impact of a fixed kinematic turning radius on the engine power required in a turn and on the load of friction elements in the turning mechanism of a tracked vehicle equipped with turning mechanisms that have several fixed kinematic turning radii. Parameters describing the relative change of engine power in a turn, the relative change of braking power on the friction elements of the turning mechanism, and the change of efficiency coefficient of the turning mechanism depending on the relative turning radius are defined. Recommendations regarding the choice of fixed kinematic turning radii, relating to the design of the turning mechanism of a tracked vehicle, are given. © 2002 Journal of Mechanical Engineering. All rights reserved. (Keywords: tracked vehicles, turning radius, engine power, turning mechanism) 0 UVOD Obračanje goseničnega vozila se doseže s spremembo hitrosti navijanja ene v primerjavi z drugo gosenico ob hkratnem oblikovanju različnih vlečnih sil na gosenicah ([1] in [2]). Dotikalni del gosenice dobiva ob vzdolžnem pomikanju pri obračanju še dodatno bočno premikanje po tleh. Zaradi vzdolžnih pomikov gosenice se pojavljajo odpori tudi pri gibanju vozila naravnost. Bočni pomiki gosenic povzročajo dodatne odpore zaradi bočnega trenja med gosenicami in tlemi, kakor tudi zaradi gnetenja, rezanja in premikov tal pod gosenicami. Zaradi tega se pojavi pri vstopu v obračanje goseničnega vozila porast skupnih odporov gibanja, zaradi česar se poveča obremenitev pogonskega motorja in pogonskega mehanizma, posledično pa tudi poveča obremenitev posameznih elementov v mehanizmih obračanja. Obremenitev motorja in pogonskega mehanizma goseničnega vozila ter posameznih elementov v mehanizmih za obračanje je v veliki meri 0 INTRODUCTION Turning a tracked vehicle is accomplished by changing the winding speed of one of its tracks with respect to the other, resulting in the simultaneous occurrance of different tractive forces on each track ([1] and [2]). The leaning part of the track, apart from the longitudinal, receives an additional lateral shift dur-ing the turn. Longitudinal shifts of the tracks induce the same kind of resistances as during rectilinear motion of the vehicle. Lateral shifts induce additional resistances due to lateral friction between the tracks and the ground and due to the compression, cutting and mixing of soil under the tracks. When a turn begins, the total resistance to motion of a tracked vehicle is increased, this causes an increased load on the engine and transmission, and therefore an increased load on the elements of the turning mechanisms. The loads on the engine and transmission of a tracked vehicle, as well as on the elements of its turning mechanisms, significantly depend on the gfin^OtJJIMISCSD 02-8 stran 459 |^BSSITIMIGC Stojkovi} V. - Mikuli} D.: Vpliv ra~unskega polmera - The Impact of a Kinematic Turning Radius odvisna od velikosti t.i. računskega polmera obračanja R . Računski polmer obračanja je tisti polmer obračanja, ki se realizira ob fiksnem prenosnem razmerju pogonske verige do notranje gosenice in brez drsenja drsnih elementov v mehanizmih obračanja ([1] in [2]). V tem prispevku je analiziran vpliv velikosti računskega polmera obračanja na potrebno moč motorja v obračanju in na obremenjenost drsnih elementov mehanizma obračanja na konkretnem primeru goseničnega vozila, ki ima mehanizme obračanja z več računskimi polmeri obračanja. Definirani so parametri, ki opisujejo relativno spremembo potrebne moči motorja pri obračanju, relativno spremembo zavorne sile na drsnih elementih mehanizma za obračanje in spremembo koeficienta koristnega delovanja mehanizma obračanja v odvisnosti od relativnega polmera obračanja. Na podlagi izvedene analize so dana priporočila za izbiranje računskega polmera obračanja. 1 DEFINIRANJE PARAMETROV ZA ANALIZIRANJE OBRAČANJA Analizirano je obračanje goseničnega vozila na vodoravni podlagi (sl. 1 in 2), ob naslednjih predpostavkah in omejitvah: - zanemarjeno je podrsavanje zunanje in notranje gosenice, - predpostavljena širina sledi gosenice je ena (B = 1), - zanemarjen je vpliv sredobežne sile, - predpostavljena teža vozila je ena (G = 1), - analizirano je obračanje s polmerom obračanja R v območju od obračanja okoli notranje gosenice do obračanja s prostim polmerom obračanja. Prosti polmer obračanja je tisti, pri katerem je sila na notranji gosenici enaka nič (F1 = 0). Pri obračanjih ki so večja od prostega polmera obračanja, na notranji gosenici nastane vlečna sila, pri polmerih obračanja, ki so manjši od prostega polmera obračanja, pa se na notranji gosenici formira zavorna sila ([1] in [2]). Na sliki 1 so prikazane sile in vrtilni momenti, ki delujejo na gosenično vozilo: R2 = odpor pri gibanju naravnost na zunanji gosenici, R1 = odpor pri gibanju naravnost na notranji gosenici F2 = vlečna sila na zunanji gosenici, F1 = zavorna sila na notranji gosenici, M = moment bočnih odporov obračanja. Odpora pri gibanju naravnost R1 in R ter moment bočnega odpora obračanja M, se določajo z izrazi ([1] in [2]): magnitude of the so-called fixed kinematic turning radius Rp. The fixed kinematic turning radius is the turning radius realized with a fixed transmission ratio of a kinematic chain to an inner track and without any sliding of the friction elements in the turning mechanism ([1] and [2]). This paper analyzes the impact of the fixed kinematic turning radius on the engine power required in a turn and on the load of the friction elements of the turning mechanism by using the concrete example of a tracked vehicle equipped with turning mechanisms that have several fixed kinematic turning radii. The parameters that describe the relative change of the required engine power in a turn, the relative change of the braking power on the friction elements of the turning mechanism, and the change of the efficiency coefficient of the turning mechanism depending on the relative turning radius are defined. On the basis of the performed analysis, recommendations regarding the choice of fixed kinematic turning radii are given. 1 DEFINITION OF PARAMETERS FOR ANALYZING A TURN The turn of a tracked vehicle on a horizontal surface (Figs. 1 and 2) is analyzed with the following assumptions and constraints: - sliding of the outer track and the inner track is neglected, - the distance between the tracks is assumed to be one (B = 1), - the influence of centrifugal force is neglected, - the vehicle’s weight is assumed to be one (G = 1), - turns with turning radii R in the interval ranging from a turn around the inner track to a turn with a free turning radius are analyzed. The free turning radius is characterized by the force on the inner track being zero (F1 = 0). For turns with radii larger than the free turning radius a tractive force is induced on the inner track, while for turns with radii less than the free turning radius a braking force is induced on the inner track ([1] and [2]). The forces and torques acting on a tracked vehicle are presented in Figure 1: R2 = resistance to rectilinear motion on the outer track, R1 = resistance to rectilinear motion on the inner track, F2 = tractive force on the outer track, F1 = braking force on the inner track, Mc = turning resistance torque. Resistances to rectilinear motion R1 and R2, and the turning resistance torque Mc are determined by the following expressions ([1] and [2]): R1 = 0,5 f G R2 = 0,5 f G Mc = mGL 4 (1), (2), (3), VBgfFMK stran 460 Stojkovi} V. - Mikuli} D.: Vpliv ra~unskega polmera - The Impact of a Kinematic Turning Radius F2 r> F1 L R2 C Mc r Y R1 Sl.1. Sile in momenti, ki delujejo pri obračanju goseničnega vozila Fig. 1. Forces and torques on a tracked vehicle in a turn m = m maks 0,925 + 0,15r (4), kjer so: f = koeficient odpora pri gibanju naravnost na določeni podlagi, r = relativni polmer obračanja (r = R/B), m = koeficient odpora obračanja na določeni podlagi in za določeni relativni polmer obračanja, mm k = koeficient odpora obračanja na določeni podlagi pri r = 0,5, L = dolžina dotikalnega dela gosenice. Vlečna sila na zunanji gosenici F2 in zavorna sila na notranji gosenici F1 lahko določimo z izrazoma ([1] in [2]): F2=R2 F1 =-R1 Na sliki 2 so prikazane hitrosti vozila pri obračanju in relativni polmeri obračanja goseničnega vozila: v2 = hitrost goseničnega vozila na zunanji gosenici, v1 = hitrost goseničnega vozila na notranji gosenici, where: f = the rectilinear motion resistance coefficient for a particular surface, r = the relative turning radius (r = R/B), m = the turning resistance coefficient for a particular surface and a particular relative turning radius, mmax = the turning resistance coefficient for a particular surface at r = 0.5, L = the length of the leaning part of a track. The tractive force on the outer track F2 and the braking force on the inner track F1 can be determined by the following expressions ([1] and [2]): (5), (6). Mc B Mc + B Figure 2 presents the velocities and relative turning radii of a turning tracked vehicle: v2 = the velocity of a tracked vehicle on the outer track, v1 = the velocity of a tracked vehicle on the inner track, vR Sl.2. Načrt hitrosti goseničnega vozila pri obračanju Fig. 2. Velocity plan of a turning tracked vehicle I IgfinHŽslbJlIMlIgiCšD I stran 461 glTMDDC Stojkovi} V. - Mikuli} D.: Vpliv ra~unskega polmera - The Impact of a Kinematic Turning Radius v = hitrost težišča goseničnega vozila, v c = hitrost točke vozila, ki ohranja enako hitrost pri obračanju in pri gibanju naravnost, qM = kinematski parameter mehanizma obračanja (relativna koordinata točke vozila, ki ima hitrost v0). Uvedimo parameter qR, ki zadovoljuje naslednji pogoj [3]: vc = the velocity of the center of mass of a tracked vehicle, v0 = the velocity of a point on the vehicle which retains the same velocity in a turn as in rectilinear motion, qM = the kinematic parameter of the turning mechanism (relative coordinate of a point on the vehicle with velocity v0). Let us introduce parameter qR, satisfying the following condition [3]: .. (R1 + R2) qR B = Mc (7). Z uporabo izraza (7) uvajamo povezanost med momentom odpora obračanju M in momentom vsote odporov pri gibanju naravnost (R1 + R2)B. Po uvrstitvah izrazov (1), (2), in (3) v izraz (7) dobimo: Expression (7) describes the correlation between the turning resistance torque Mc and the torque of the sum of resistances to rectilinear motion . (R1 + R2) B. Inserting (1), (2) and (3) into (7) results in the following expression: mL qR = 4 fB (8). Uvedemo pojem relativnega računskega polmera obračanja rp: r Pri obračanju goseničnega vozila, razen odporov pri gibanju naravnost(R1 + R2), obstajajo tudi dodatni bočni odpori, ki oblikujejo moment odpora obračanja M. Potrebna moč za obvladovanje skupnih zunanjih odporov obračanja (P0) je večja od potrebne moči za premagovanje odporov pri gibanju naravnost (Pp) ([3] in [4]): The relative fixed kinematic turning radius rp is defined as: Rp = B (9). Besides resistances to rectilinear motion (R1 + R2), there are additional lateral resistances, which form the turning resistance torque Mc in the turning movement of a tracked vehicle. The power required for overcoming the total external resistances in a turn (P0) is larger than the power required for overcoming the resistance in rectilinear motion (Ppr) ([3] and [4]): P = (R + R ) v 1 2 0 P0 = (R1 + R2)v0 qR +r qM +r P =P Potrebna moč motorja za izvedbo obračanja goseničnega vozila (P ) se določi z izrazom ([3] in [4]): (10), (11), (12). qM +r The engine power required for accomplishing the turn of a tracked vehicle (Pmz) is determined by the following expressions ([3] and [4]): qR +r Pmz = (R1 + R2 )v0 qR +rp P =P mz pr qM +rp qR +rp Pri obračanju goseničnega vozila s polmeri obračanja, ki so različni od računskih, se na drsnih elementih mehanizma za obračanje sprošča moč drsenja (Pk), ki se določa z izrazom ([3] in [4]): Pk=(R1+R2)v0 (13), (14). qM +rp The power of sliding (Pk) that is spent on the friction elements of the turning mechanism during the turns of a tracked vehicle at turning radii different from the fixed kinematic turning radius is determined by the following expression ([3] and [4]): qR -qM r -rp qM qR -qM rpqM r-rp r (15), (16). qm+rpqm+r Uvedimo koeficient relativne potrebne moči The coefficient of relative engine power motorja pri obračanju (ymz), koeficient relativne moči required in a turn (ymz), the coefficient of relative VH^tTPsDDIK stran 462 Stojkovi} V. - Mikuli} D.: Vpliv ra~unskega polmera - The Impact of a Kinematic Turning Radius drsenja v drsnih elementih mehanizma za obračanje yk in koeficient koristnega delovanja mehanizma obračanja hm , in sicer ([3] in [4]): power of sliding in the friction elements of the turning mechanism yk, and the efficiency coefficient of the turning mechanism hmz are defined as ([3] and [4]): ym y P pr qR +rp mz qM +rp P yk = P pr qR -qM r - rp qM +rp qM P +r h mz = P mz qR +r qM +rp yk qm+r qr+r Na podlagi gornjih izrazov lahko povzamemo, da se koeficient relativne potrebne moči motorja pri obračanju ym , koeficient relativne moči podrsavanja v drsnih elementih mehanizma obračanja yk in koeficient koristnega delovanja mehanizma obračanja hm spreminjajo v odvisnosti od: -" koeficienta odpora gibanja f na tleh, kjer se obrača, - relativnega polmera obračanja r, - relativnega proračunskega polmera obračanja p in - parametra gibanja qM . Idealen mehanizem obračanja bi bil tisti, pri katerem bi za vsak relativni polmer obračanja dosegli y =1, yk = 0 in hm = 1. Vrednosti koeficientov ym , yk in hm za realni mehanizem obračanja pričajo o stopnjf uspešnosti projektnega oblikovanja mehanizma obračanja z vidika smotrne rabe moči motorja, a posredno tudi o njegovem vplivu na porabo pogonskega goriva. 2 ANALIZA VPLIVA VELIKOSTI RAČUNSKEGA POLMERA OBRAČANJA Za izvajanje analize je izbran mehanizem obračanja na goseničnem vozilu BVP - M80, katerega shema gibanja [5] je prikazana na sliki 3. Prikazan mehanizem obračanja sodi v skupino t.i. pogonskih prenosov v bloku (TUB), pri katerih je pogonsko in konstrukcijsko združena funkcija menjanja stopnje prenosa v menjalniku in menjanje hitrosti obračanja pogonskih koles pri obračanju goseničnega vozila. Ta pogonski prenos v bloku je sestavljen iz menjalnika (MJ), zbirnih diferencialov (SD2 in SD1), pomožnih drsnih spojk (fn2 in), pomožnih drsnih zavor (T in T 1) in drsnih zavor fn1 za zaustavljanje (T02 in T01). S sprožitvijo drsne zavore T0 v TUB do notranje gosenice nastane najmanjši relativni računski polmer obračanja rp0 = 0,5. S popolnim proženjem pomožne drsne spojnice fn v TUB do notranje gosenice nastane še po en relativni računski polmer obračanja v vsaki stopnji prenosa (rp = 1,2; rp = 3,1; rp3 = 4,8; rp = 7,5; p5 = 11,1). Obračanje s preostalimi polmeri obračanja (17), (18), (19), (20), (21), (22). These expressions show that the coefficient of relative engine power required in a turn ymz, the coefficient of relative power of sliding in the friction elements of the turning mechanism yk, and the efficiency coefficient of the turning mechanism hmz depend on: - the rectilinear motion resistance coefficient f for a particular surface, - the relative turning radius r, - the relative fixed kinematic turning radius rp, - the kinematic parameter qM. An ideal turning mechanism would achieve ymz = 1, yk = 0 and hmz = 1 for every turning radius. For real turning mechanisms the values of the coefficients ymz, yk and hmz indicate the quality of design, regarding rational use of engine power, and indirectly influence fuel consumption. 2 AN IMPACT ANALYSIS FOR A FIXED KINEMATIC TURNING RADIUS The analysis is conducted on the turning mechanism of the BVP-M80 tracked vehicle. Its kinematic scheme [5] is presented in Figure 3. This turning mechanism belongs to the category of the so-called block transmissions (BT). In block transmissions the functions of changing gears in a gearbox and of changing the rotation speed of the propulsion wheels during a turn are kinematically and constructionally unified. The presented block transmission consists of a gearbox (MJ), summing differentials (SD2 and SD1), auxiliary friction clutches (fn2 and fn1), auxiliary friction brakes (Tn2 and Tn1), and halting friction brakes (T02 and T01). By activating a halting friction brake T0 in the BT to the inner track, the minimum relative fixed kinematic turning radius of rp0 = 0.5 is realized. By fully activating an auxiliary friction clutch fn in the BT to the inner track, yet another relative fixed kinematic turning radius is realized for each gear (rp1 = 1.2; rp2 = 3.1; rp3 = 4.8; rp4 = 7.5; rp5 = 11.1). Turns Stojkovi} V. - Mikuli} D.: Vpliv ra~unskega polmera - The Impact of a Kinematic Turning Radius SD2 — T n2 T n1 _ SD1 Sl. 3. Shema gibanja mehanizma obračanja goseničnega vozila BVP M-80 Fig. 3. Kinematic scheme of the turning mechanism of the BVP-M80 tracked vehicle nastane z drsenjem enega od drsnih elementov v TUB (^ ali T ali T0). n Za gosenično vozilo BVP M-80 (5) so znane vrednosti [5] qM = 0,5 in L/B = 1,3. Analiziramo obračanje z vozilom na vodoravni s travo pokriti podlagi z osvojenima koeficientoma ([1] in [2]) f = 0,06 in// = 0,8. Grafični prikaz rezultatov računanja koeficientov ym , yk in ij , za izbrano vozilo je podan na slikah 4, 5 in 6. Pri analizi dobljenih rezultatov je opazno naslednje: - večanje relativnega računskega polmera obračanja vpliva na zmanjševanje koeficientov relativne potrebne moči motorja pri obračanju ym in koeficienta relativne zavorne moči yLob povečanju koeficienta koristnega delovanja mehanizma obračanja t, za relativne polmere with other turning radii are realized by sliding one of the friction elements in the BT (fn or Tn or T0). For the BVP M-80 tracked vehicle, the following values are known [5]: qM = 0.5 and L/B = 1.3. The turn of the vehicle on a horizontal sodded-grass surface is analyzed with the assumed coefficients ([1] and [2]) f = 0.06 and mmax = 0.8. Graphs of the coefficients ymz, yk and hmz are calculated for the chosen vehicle and presented in Figures 4, 5 and 6. Analysis of the results shows that: - with the increase of the relative fixed kinematic turning radius, the coefficient of relative engine power required in a turn ymz decreases, as does the coefficient of the relative power of sliding in the friction elements of the turning mechanism yk, while the efficiency coefficient of the turning mechanism hmz increases for relative turning radii Sl. 4. Koeficient relativne potrebne moči motorja pri obračanju Fig. 4. Coefficient of relative engine power required in a turn Sl. 5. Koeficient relativne moči drsenja v mehanizmu obračanja Fig. 5. Coefficient of relative power of sliding in the turning mechanism VH^tTPsDDIK stran 464 Stojkovi} V. - Mikuli} D.: Vpliv ra~unskega polmera - The Impact of a Kinematic Turning Radius 1,0 h mz 0,9 0,8 0,7 0,6 0,5 0,4 0,3 iw . ---*^ ___--- s^-rp' „ - ! rp2 # >^ ¦ * * \ \rp1 * \rp0 10 20 30 40 50 Sl. 6. Koeficient koristnega dela mehanizma obračanja Fig. 6. Efficiency coefficient of the turning mechanism obračanja r, ki so večji od relativnega računskega polmera obračanja za posamezno stopnjo prenosa, - zmanjševanje koeficientov ym in yk ter povečanje koeficienta hm je posebno izraženo v območju relativnega računskega polmera rpi e {1,0; 5,0}, - za intervale računskih polmerov/ e {5,1; 15,0} je gibanje ugodnih vrednosti koeficientov ym , yk in hm majhne intenzivnosti, - obstoj "več relativnih računskih polmerov obračanja, ki se medsebojno razlikujejo po velikosti, omogoča prehod obračanja goseničnih vozil z višje ravni (rp ) na sosednjo nižjo raven (rpi-1) v primeru, ko je treba izvesti obračanje z relativnim polmerom, ki je manjši od rp in večji od rp0 = 0,5, - prehod obračanja goseničnega vozila z višje ravni (rp ) na sosednjo nižjo raven (rpi-1) v primeru, ko je treba izvesti obračanje z relativnim polmerom, manjšim od ( ), a večjim od rp = 0,5, zmanjšuje obremenitev rpi pogonskega motorja in drsnih elementov mehanizma obračanja. 3 SKLEP Pri izvajanju manevra obračanja goseničnega vozila se z zmanjševanjem polmera obračanja pojavljajo povečani odpori obračanja in povečane obremenitve pogonskega motorja in sklopov v prenosnem mehanizmu za gibanje vozila. Obstoj relativnih računskih polmerov obračanja, ki so večji od rp = 0,5, prispeva k zmanjševanju obremenitev pogonskega motorja in elementov v prenosih v primeru obračanja s polmeri obračanja, ki so enaki ali večji od relativnega računskega polmera obračanja. Koeficienti relativne potrebne moči motorja pri obračanju (ym ), relativne zavorne moči (yk) ter koeficient koristnega delovanja mehanizma obračanja (hm ) imajo ugodne vrednosti za to območje obračanja. r that are larger than the relative fixed kinematic turning radius rpi for the particular gear, the decrease of ymz and yk and the increase of hmz are particularly pronounced in the interval of the relative fixed kinematic turning radii rpi 1.0; 5.0}, - in the interval of relative fixed kinematic turning radii rp e {5.1; 15.0} the favorable trend of values of the i coefficients ym , yk and hm is more moderate, - the existence of several relative fixed kinematic turning radii that are different in magnitude allows transitioning from a higher (rp ) to the nearest lower level (rp 1), for the case when a turn with relative radius less than rp and larger than rp = 0.5 is required, - transitioning from a higher (rp ) to the nearest lower level (rp 1), for the case when a turn with a relative radius less than rp and larger than rp0 = 0.5 is required, decreases the engine load and the load on the friction elements of the turning mechanism. 3 CONCLUSION The decrease in turning radius during the turn of a tracked vehicle leads to increased turning resistances, an increased engine load and an increased load on the transmission devices of the vehicle. The existence of relative fixed kinematic turning radii larger than = 0.5 enables a decrease in the engine load and the rp0 load on the transmission elements for the cases of turns with turning radii greater than or equal to the relative fixed kinematic turning radius. The coefficient of relative engine power required in a turn (ym ), the coefficient of relative braking power (yk), and the efficiency coefficient of the turning mechanism ( ) have favorable values for those turning radii. hmz - Stojkovi} V. - Mikuli} D.: Vpliv ra~unskega polmera - The Impact of a Kinematic Turning Radius Ugodno gibanje vrednosti koeficientov ym , yk in rj je posebej izraženo pri relativnih računskih polmerih obračanja v območju p e {1,0; 5,0}. Za intervale relativnih računskih polmerov p i e {5,1; 15,0} je gibanje ugodnih vrednosti koeficientov ym , yk in rj umirjene intenzivnosti. V področju obračanja v katerem bi se uporabili relativni računski polmeri obračanja, ki so večji odp = 15, se koeficienti ym , yk inij le malo spreminjajo. i " Ob projektiranju novih pogonskih prenosov za gosenična vozila je zato priporočljivo uporabiti en računski polmer obračanja p 0 = 0,5 in več relativnih računskih polmerov obračanja v območju p e { 1,0; 15,0}. A favorable trend of values of the coefficients ym , yk andr, is particularly pronounced for relative fixed kinematic turning radii in the interval p e {1.0; 5.0}. In the interval of relative fixed kinematic turning radiip e { 5.1; 15.0} the favorable trend of values of ym , yk and rj is more moderate. In the range of turns with relative fixed kinematic turning radii larger than p = 15, the coefficients ym , yk and rj do not change i significantly. When designing the transmission of a tracked vehicle it is desirable to realize one fixed kinematic turning radius p = 0.5 and several other fixed kinematic turning radii in the interval p e { 1.0; 15.0}. 4 LITERATURA 4 REFERENCES [1] Zabavnikov, N. A. (1975) Osnovy teorii transportnyh gusenicnyh mašin, Masinostroenie, Moskva. [2] Farobin, J. E .(1970) Teorija povorota transportnyh mašin, Masinostroenie, Leningrad. [3] Nosov, N. A. (1972) Rasčet i konstruirovanie gusenicnyh mašin, Masinostroenie, Leningrad. [4] Krasnenkov V. I., A.D. Vašec (1986) Proektirovanie planetarnih mehanizmov transportnyh mašin, Masinostroenie, Moskva. [5] Borbeno vozilo pešadije BVP M-80A, TU-I, SSNO, Beograd, 1989. Naslova avtorjev: dr. Vjekoslav Stojkovic Ministrstvo za obrambo Inštitut obrambnih študij, raziskav in razvoja Bijenička cesta 46 10000 Zagreb, Hrvaška vjekoslav.stojkovic@morh.hr Dr. Dinko Mikulič Ministrstvo za obrambo Uprava za opremljanje in nabavo Trg Petra Kresimira IV. br. 1 10000 Zagreb, Hrvaška dmikulic@net.hr Author’s Address:Dr. Vjekoslav Stojkovič. Ministry of Defence Institute for Defence Studies, Researches & Development Bijenička cesta 46 HR-10000 Zagreb, Croatia vjekoslav.stojkovic@morh.hr Dr. Dinko Mikulič Ministry of Defence Dept. for Acquisition & Procurement Trg Petra Kresimira IV. br. 1 HR-10000 Zagreb, Croatia dmikulic@net.hr Prejeto: Received: 7.1.2002 Sprejeto: Accepted: 20.9.2002 VH^tTPsDDIK stran 466