Fig. 1.
![Forces acting on a farm tractor (ISO coordinate system [35])](https://sciendo-parsed.s3.eu-central-1.amazonaws.com/67f3415f8d1bec042eac83d9/j_ama-2025-0012_fig_001.jpg?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential=ASIA6AP2G7AKL3MB22LX%2F20251216%2Feu-central-1%2Fs3%2Faws4_request&X-Amz-Date=20251216T003136Z&X-Amz-Expires=3600&X-Amz-Security-Token=IQoJb3JpZ2luX2VjEI7%2F%2F%2F%2F%2F%2F%2F%2F%2F%2FwEaDGV1LWNlbnRyYWwtMSJHMEUCIQD8WGxrtNfxZu341od%2FsrGm2xG09JV8s6kBxqoXRpgVeQIgGPJvgetUZdmHU6WDi0dh3rNFOObwwbg%2FMKtadkbT%2Fa8qvAUIVxACGgw5NjMxMzQyODk5NDAiDCH2FLfB1suC370JsSqZBZ4DC6trXGvrfBw%2F%2BgeXfHZp5xwREribyX59OGZ5B64IJ0SmFeBGrD4yVmxttUZ%2B2mxgCq9HRzkRhPop5Uap2hvjSG4Cgl3dL0j0cjb6rJrOITiEY6BVhNXEYXe7LX7%2FD7lKb4cdfbSBwIysc5AjlaVyPoTCcBX1bzTnXvE1XGwK4LgiQzyEY1LUEbE12pC4dS1UczR37Izw8aCsR0U7aBWAEe0jOSz2uQrxCXAH5HjEmeYE08nZu79e%2FePalAlVboM1hQeK4tIczRocvkkEpHtOGw8S5ZF7jOWTC2XKIC6yrSf4KVpeeyMqUN%2BSqvu70pgbXip%2BK20UF0ftw%2FPFh87E1qfGE5p3tuVHiZil7hQymx3vSXBSrYydXAmG8g5b%2Bs2XO4fQirIx%2FQza5wJTN2us8emMg9wgCiuV3ZgmYnjvujKvS2q%2B5xgjKTh0MGkwTs1hB7fN5CJXF7JVzy5xacTnI7hOu%2B2HZE10TAQfWBMUrJcSoVF2WmvhAKvTSWolwa7nw6lUwVMSjb50mPTIjBOT51gJysa9sFn%2BwLNBAyCSheUE4zCwIyc9fWuskxzsMDR7yEZg%2B7Ue4AhvZq3QWhBj2wEXxuL6mPN2zWs73nFcb8MOdKq6G840831S9FQ6GcnIQRBt%2ByJtYUeTd2ZBoGnpoik%2Ff6N0YdWc2gPFoKFlj6relz80CkznfXxH3UQk67qkA6KUgktMs8Pw7cZSh8Q%2B9SNWScQmM7Y6rqUZC2%2FZRhrkQ4yPn42tNYc%2F6cYnCkXFSyRueBJLlDWOSvEtA0hngLaGYAxgMpLfL23pixqC74vsXL5IFdN3yPfhV1nGn2snpeWvJwFtUpb%2FkEfo9je3xvjvAoUOcP3zs6MaFPUqfmISNPisOS69MO2NgsoGOrEBayWCTRAtyfQ15vXUhCeN875%2FPDb4DZ2yIIA9kvxf8WNL4lSqbmcioA0elRdKNSTJdnOLhKXu3eCg04DsOF6YKxB0F4C8jt8GGPwq82bBL4FTJrWFaUc%2FgUR1l%2BDRL8EJXU0oZxlyc5yawHKSBtIGkmCrKxpoA8sn33JN%2FiXBWaMQBA3Dqor6nQ%2FmC0XrdrB0%2FQK49JVOagybqOxn8VwgdoxOqju4HwdGQ15LcsyKoynd&X-Amz-Signature=cdb3d802fd755aa1afe86e6225c8ad406c1d0d533ea8ebf9e3b470242293419f&X-Amz-SignedHeaders=host&x-amz-checksum-mode=ENABLED&x-id=GetObject)
Fig. 2.

Fig. 3.

Fig. 4.

Fig. 5.

Fig. 6.

Fig. 7.

Fig. 8.

Fig. 9.
![Limits of adhesion utilization in accordance with Commission Delegated Regulation (EU) 2015/68 [8]: a – first solution, b – second solution](https://sciendo-parsed.s3.eu-central-1.amazonaws.com/67f3415f8d1bec042eac83d9/j_ama-2025-0012_fig_009.jpg?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential=ASIA6AP2G7AKL3MB22LX%2F20251216%2Feu-central-1%2Fs3%2Faws4_request&X-Amz-Date=20251216T003136Z&X-Amz-Expires=3600&X-Amz-Security-Token=IQoJb3JpZ2luX2VjEI7%2F%2F%2F%2F%2F%2F%2F%2F%2F%2FwEaDGV1LWNlbnRyYWwtMSJHMEUCIQD8WGxrtNfxZu341od%2FsrGm2xG09JV8s6kBxqoXRpgVeQIgGPJvgetUZdmHU6WDi0dh3rNFOObwwbg%2FMKtadkbT%2Fa8qvAUIVxACGgw5NjMxMzQyODk5NDAiDCH2FLfB1suC370JsSqZBZ4DC6trXGvrfBw%2F%2BgeXfHZp5xwREribyX59OGZ5B64IJ0SmFeBGrD4yVmxttUZ%2B2mxgCq9HRzkRhPop5Uap2hvjSG4Cgl3dL0j0cjb6rJrOITiEY6BVhNXEYXe7LX7%2FD7lKb4cdfbSBwIysc5AjlaVyPoTCcBX1bzTnXvE1XGwK4LgiQzyEY1LUEbE12pC4dS1UczR37Izw8aCsR0U7aBWAEe0jOSz2uQrxCXAH5HjEmeYE08nZu79e%2FePalAlVboM1hQeK4tIczRocvkkEpHtOGw8S5ZF7jOWTC2XKIC6yrSf4KVpeeyMqUN%2BSqvu70pgbXip%2BK20UF0ftw%2FPFh87E1qfGE5p3tuVHiZil7hQymx3vSXBSrYydXAmG8g5b%2Bs2XO4fQirIx%2FQza5wJTN2us8emMg9wgCiuV3ZgmYnjvujKvS2q%2B5xgjKTh0MGkwTs1hB7fN5CJXF7JVzy5xacTnI7hOu%2B2HZE10TAQfWBMUrJcSoVF2WmvhAKvTSWolwa7nw6lUwVMSjb50mPTIjBOT51gJysa9sFn%2BwLNBAyCSheUE4zCwIyc9fWuskxzsMDR7yEZg%2B7Ue4AhvZq3QWhBj2wEXxuL6mPN2zWs73nFcb8MOdKq6G840831S9FQ6GcnIQRBt%2ByJtYUeTd2ZBoGnpoik%2Ff6N0YdWc2gPFoKFlj6relz80CkznfXxH3UQk67qkA6KUgktMs8Pw7cZSh8Q%2B9SNWScQmM7Y6rqUZC2%2FZRhrkQ4yPn42tNYc%2F6cYnCkXFSyRueBJLlDWOSvEtA0hngLaGYAxgMpLfL23pixqC74vsXL5IFdN3yPfhV1nGn2snpeWvJwFtUpb%2FkEfo9je3xvjvAoUOcP3zs6MaFPUqfmISNPisOS69MO2NgsoGOrEBayWCTRAtyfQ15vXUhCeN875%2FPDb4DZ2yIIA9kvxf8WNL4lSqbmcioA0elRdKNSTJdnOLhKXu3eCg04DsOF6YKxB0F4C8jt8GGPwq82bBL4FTJrWFaUc%2FgUR1l%2BDRL8EJXU0oZxlyc5yawHKSBtIGkmCrKxpoA8sn33JN%2FiXBWaMQBA3Dqor6nQ%2FmC0XrdrB0%2FQK49JVOagybqOxn8VwgdoxOqju4HwdGQ15LcsyKoynd&X-Amz-Signature=8187fb5039a48922f5db6853ac2b9b562c45a137e25e579c06947ed146711959&X-Amz-SignedHeaders=host&x-amz-checksum-mode=ENABLED&x-id=GetObject)
Fig. 10.

Fig. 11.

Fig. 12.

Fig. 13.

Rigid drawbar trailer and tandem suspension technical data [37–38]
| Semi-trailer with tandem axle | Tandem suspension | |||||
|---|---|---|---|---|---|---|
| unladen | laden | bogie (3.1) | 2 leaf spring (3.2) | 2 leaf 2 rod (3.3) | 2 leaf equal. (3.4) | air susp. (3.5) |
| m=3900 kg | m=19800 kg | d1=0.705 m | c1=0.454 m | c1=0.497 m | c1=0.454 m | c1=0.5 m |
| L1=3.94 m | L1=3.94 m | d2=0.645 m | c=0.93 m | c=0.97 m | c=0.93 m | c=0.88 m |
| L2=1.35 m | L2=1.35 m | hs=0.567 m | hs=0.717 m | hr1=hr1=0.467 m | hs=0.717 m | hs=0.717 m |
| a=4.26 m | a=4.055 m | h2=0.547 m | h2=0.567 m | h2=0.567 m | h2=0.567 m | h2=0.567 m |
| h=1.19 m | h=1.62 m | b2=0.03 m | d1=d2=0.21m | d1=d2=0.19 m | d1=d2=0.675 m | |
| hh=0.59 m | hh=0.59 m | α1= α2=15º | ||||
The technical data and results of the optimization of brake force distribution in single axle semi-trailer: L1=4_45 m, hh=0_7 m (L ‒ laden, U ‒ unladen, I, II – first and second solution)
| m kg] | a [m] | h [m] | OF | β1 | iP | |
|---|---|---|---|---|---|---|
| UI-UII | 2250 | 3.895 | 0.98 | 0.0947–0.0947 | 0.2079–0.2079 | 3.8097–3.8097 |
| LI - LII | 7250 | 3.840 | 1.25 | 0.1272–0.1272 | 0.2445–0.2445 | 3.0901–3.0901 |
The results of the optimization of brake force distribution in a tandem axle semi-trailer (L ‒laden, U ‒ unladen, Lw, Uw – laden and unladen with weight of suspension)
| Suspension | OF | β1 | β21 | β22 | iP | iS | |
|---|---|---|---|---|---|---|---|
| Bogie (3.1) | U-Uw | 0.3040–0.3115 | 0.1629–0.1588 | 0.5740–0.5793 | 0.2631–0.2619 | 5.1402–5.2971 | 0.4583–0.4521 |
| I and II solution | L-Lw | 0.3006–0.3015 | 0.2301–0.2301 | 0.5286–0.5286 | 0.2412–0.2412 | 3.3456–3.3456 | 0.4564–0.4564 |
| 2 leaf 2 rod (3.3) | U-Uw | 0.6716–0.8831 | 0.2313–0.2307 | 0.1803–0.1527 | 0.5884–0.6166 | 3.3239–3.3354 | 3.2635–4.0377 |
| I solution | L-Lw | 0.5841–0.6991 | 0.3117–0.3267 | 0.1674–0.1644 | 0.5209–0.5189 | 2.2086–2.1574 | 3.1116–3.1573 |
| II solution | U-Uw | 0.9446–1.2169 | 0.2075–0.2065 | 0.1705–0.1444 | 0.6220–0.6490 | 3.8198–3.8417 | 3.6483–4.4935 |
| L-Lw | 0.7531–0.7893 | 0.2806–0.2818 | 0.1577–0.1525 | 0.5617–0.5657 | 2.5635–2.5490 | 3.5631–3.7096 | |
| 2 leaf equal. (3.4) | U-Uw | 0.2512–0.2512 | 0.1951–0.1951 | 0.4031–0.4031 | 0.4018–0.4018 | 4.1265–4.1265 | 0.9969–0.9969 |
| I solution | L-Lw | 0.2099–0.2099 | 0.2605–0.2605 | 0.3710–0.3710 | 0.3685–0.3685 | 2.8388–2.8388 | 0.9935–0.9935 |
| II solution | U-Uw | 0.3002–0.3002 | 0.1803–0.1803 | 0.4040–0.4040 | 0.4156–0.4156 | 4.5449–4.5449 | 1.0288–1.0288 |
| L-Lw | 0.2117–0.2117 | 0.2561–0.2561 | 0.3721–0.3721 | 0.3717–0.3717 | 2.9046–2.9046 | 0.9989–0.9989 | |
| air susp. (3.5) | U-Uw | 0.2511–0.2511 | 0.1951–0.1951 | 0.4031–0.4031 | 0.4018–0.4018 | 4.1265–4.1265 | 0.9969–0.9969 |
| I solution | L-Lw | 0.2098–0.2098 | 0.2605–0.2605 | 0.3710–0.3710 | 0.3685–0.3685 | 2.8388–2.8388 | 0.9935–0.9935 |
| II solution | U-Uw | 0.3003–0.3003 | 0.1803–0.1803 | 0.4040–0.4040 | 0.4156–0.4156 | 4.5449–4.5449 | 1.0288–1.0288 |
| L-Lw | 0.2117–0.2117 | 0.2561–0.2561 | 0.3721–0.3721 | 0.3717–0.3717 | 2.9046–2.9046 | 0.9989–0.9989 | |
| 2 leaf (3.2) only | U-Uw | 5.3013–3.5221 | 0.2271–0.2337 | 0.0017–0.0218 | 0.7712–0.7446 | 3.4025–3.2798 | 458.23–34.199 |
| I solution | L-Lw | 4.6761–4.5855 | 0.3230–0.3202 | 0.0018–0.0030 | 0.6752–0.6768 | 2.0957–2.1233 | 376.30–222.04 |