Tá imthacaí liathróid sraith dhúbailte oiriúnach le haghaidh ualaí gathacha meánacha agus ualaí beaga aiseach sa dá threo.Tá a ndearadh agus a bhfeidhm cosúil le péire imthacaí liathróid aon sraithe.Úsáidtear na himthacaí seo in iarratais nach leor cumas ualaigh an imthacaí sraithe singil.Tá an trastomhas seachtrach céanna agus an trastomhas tollaidh céanna ag imthacaí liathróid dúbailte agus imthacaí sraithe singil, ach tá siad níos leithne agus tá cumas ualaigh i bhfad níos airde acu ná imthacaí aonair. - imthacaí liathróid as a chéile den tsraith 62 agus 63.
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sraith dhúbailte | Uimhir imthacaí | Príomhtoisí (mm) | Bunrang rátáil ualach |
| d | D | B | r nóim. | Cr (KN) | Cor (KN) |
| 4200 T | 4200 2RS T | 10 | 30 | 14 | 0.6 | 8.69 | 4. 94 |
| 4201 T | 4201 2RS T | 12 | 32 | 14 | 0.6 | 8.835 | 5.23 |
| 4202 T | 4202 2RS T | 15 | 35 | 14 | 0.6 | 9.88 | 6.37 |
| 4203 T | 4203 2RS T | 17 | 40 | 16 | 0.6 | 13.87 | 9.03 |
| 4204 T | 4204 2RS T | 20 | 47 | 18 | 1 | 17.1 | 12.07 |
| 4205 T | 4205 2RS T | 25 | 52 | 18 | 1 | 18.34 | 13.87 |
| 4206 T | 4206 2RS T | 30 | 62 | 20 | 1 | 24.7 | 19.76 |
| 4207 T | 4207 2RS T | 35 | 72 | 23 | 1.1 | 30.4 | 24.7 |
| 4208T | 4208 2RS T | 40 | 80 | 23 | 1.1 | 32.3 | 28.5 |
| 4209 T | 4209 2RS T | 45 | 85 | 23 | 1.1 | 34.2 | 31.83 |
| 4210T | 4210 2RS T | 50 | 90 | 23 | 1.1 | 35.63 | 34.68 |
| 4211 T | 4211 2RS T | 55 | 100 | 25 | 1.5 | 34.68 | 40.85 |
| 4212 T | 4212 2RS T | 60 | 110 | 28 | 1.5 | 54.15 | 55.58 |
| 4213 T | 4213 2RS T | 65 | 120 | 31 | 1.5 | 63.65 | 63.65 |
| 4214 T | 4214 2RS T | 70 | 125 | 31 | 1.5 | 66.03 | 69.83 |
| 4215 T | 4215 2RS T | 75 | 130 | 31 | 1.5 | 69.83 | 76 |
| 4216 T | 4216 2RS T | 80 | 140 | 33 | 2 | 76 | 85.5 |
| 4217 T | 4217 2RS T | 85 | 150 | 36 | 2 | 88.35 | 100.7 |
| 4218T | 4218 2RS T | 90 | 160 | 40 | 2 | 106.4 | 115.9 |
| 4300T | 4300 2RS T | 10 | 35 | 17 | 0.6 | 14.3 | 8.9 |
| 4301 T | 4301 2RS T | 12 | 37 | 17 | 1.0 | 13 | 7.8 |
| 4302 T | 4302 2RS T | 15 | 42 | 17 | 1 | 13.87 | 8.69 |
| 4303 T | 4303 2RS T | 17 | 47 | 19 | 1 | 18.62 | 12.54 |
| 4304 T | 4304 2RS T | 20 | 52 | 21 | 1.1 | 22.04 | 15.2 |
| 4305 T | 4305 2RS T | 25 | 62 | 24 | 1.1 | 29.93 | 21.28 |
| 4306 T | 4306 2RS T | 30 | 72 | 27 | 1.1 | 38 | 28.98 |
| 4307 T | 4307 2RS T | 35 | 80 | 31 | 1.5 | 48.45 | 36.1 |
| 4308T | 4308 2RS T | 40 | 90 | 33 | 1.5 | 59.85 | 45.6 |
| 4309 T | 4309 2RS T | 45 | 100 | 36 | 1.5 | 68.4 | 57 |
| 4310T | 4310 2RS T | 50 | 110 | 40 | 2 | 85.5 | 71.25 |
| 4311 T | 4311 2RS T | 55 | 120 | 43 | 2 | 98.8 | 85.5 |
| 4312 T | 4312 2RS T | 60 | 130 | 46 | 2.1 | 114 | 100.7 |
| 4313 T | 4313 2RS T | 65 | 140 | 48 | 2.3 | 123 | 108 |
| 4314 T | 4314 2RS T | 70 | 150 | 51 | 2.3 | 135 | 108 |
| 4315 T | 4315 2RS T | 75 | 160 | 55 | 2.5 | 142 | 126 |
| 4316 T | 4316 2RS T | 80 | 170 | 58 | 3 | 158 | 132 |
