How to understand KOMATSU PC300LC-8 track roller?

РС300LC-8M0  track roller

1. Komatsu РС300LC-8M0 Carrier Rollers P/N BERCO KM3856 BERCO KM4183 KOMATSU 207-30-00550 KOMATSU 207-30-00551 VPI VKM4183V 207-30-00620  
2. Komatsu  РС300LC-8M0 Front Idlers P/N BERCO KM1927 BERCO KM2018 ITM P40304B0M00 KOMATSU 207-30-00160 KOMATSU 207-30-00161 KOMATSU 207-30-00401 KOMATSU 207-30-K1900 VPI VKM2018V 207-30-48110 
3. Komatsu  РС300LC-8M0 Sprocket 21 Teeth 20 Holes P/N: BERCO KM1921 BERCO KM2385 BERCO KM3958 BERCO KM4186 ITM R40300A0M01 KOMATSU 207-27-61210 KOMATSU 207-27-71460 VPI VKM2385V 207-27-72270 
4. Komatsu  РС300LC-8M0 sprocket bolts P/N: 207-27-51311   (M20X2.5X55)
5. Komatsu  РС300LC-8M0 track adjust assembly P/N: 207-30-00990  
6. Komatsu  РС300LC-8M0 Track shoes assembly  48L 600MM P/N: 207-32-03891 Гусеничная лента в сборе(ширина трака 800 мм.,48 звеньев) 
7. Komatsu  РС300LC-8M0 Track links assembly 48 Links P/N: BERCO KM2233/48 BERCO SI801/48 DAEWOO 200103-00067 DAEWOO 200103-00067A DAEWOO 272-00062 FIAT-HITACHI 71401513 FIAT-HITACHI 71474914 HITACHI 9167840 HITACHI 9202852 HYUNDAI 81N8-26600 ITM E40306C0M00048 ITM E40306C1M00048 JOHN DEERE AT250256 KOMATSU 207-32-00151 KOMATSU 207-32-00310 VPI VKM2233/48HDV
8. Komatsu  РС300LC-8M0 Track shoes 600MM P/N: BERCO KM2118/600 DAEWOO 200106-00148 DAEWOO 273-00102 DOOSAN K1007041 FIAT-HITACHI 71401517 HITACHI 2040403 HYUNDAI 81N8-25530 HYUNDAI 81N8-26530 ITM Z40303M0N0600 ITM Z40303M0N0600V JOHN DEERE AT219594 KOMATSU 207-32-61110 KOMATSU 207-32-62110