{"id":3243,"date":"2026-06-02T03:53:28","date_gmt":"2026-06-02T03:53:28","guid":{"rendered":"https:\/\/spiralbevelgearbox.xyz\/?p=3243"},"modified":"2026-06-02T03:53:28","modified_gmt":"2026-06-02T03:53:28","slug":"what-transmission-ratio-should-you-choose-for-a-spiral-bevel-gearbox-11-to-31-explained","status":"publish","type":"post","link":"https:\/\/spiralbevelgearbox.xyz\/ja\/application\/what-transmission-ratio-should-you-choose-for-a-spiral-bevel-gearbox-11-to-31-explained\/","title":{"rendered":"\u30b9\u30d1\u30a4\u30e9\u30eb\u30d9\u30d9\u30eb\u30ae\u30a2\u30dc\u30c3\u30af\u30b9\u306e\u5909\u901f\u6bd4\u306f\u3069\u308c\u3092\u9078\u3076\u3079\u304d\u304b\uff1f1:1\u304b\u30893:1\u307e\u3067\u89e3\u8aac"},"content":{"rendered":"
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The transmission ratio of a \u30b9\u30d1\u30a4\u30e9\u30eb\u30d9\u30d9\u30eb\u30ae\u30a2\u30dc\u30c3\u30af\u30b9<\/strong> is the single parameter most engineers look at first \u2014 and often the one that causes the most confusion in practice. A 1:1 ratio does not mean the gearbox does nothing. A 3:1 ratio does not mean you always need a slower output. This guide explains what each standard ratio actually delivers, how to calculate the output you need, and which ratio fits which industrial application.<\/p>\n

\"Ever<\/p>\n

1. What Does Transmission Ratio Mean in a Spiral Bevel Gearbox?<\/h2>\n

The transmission ratio \u2014 also called gear ratio or reduction ratio \u2014 defines the relationship between input shaft speed and output shaft speed:<\/p>\n

Ratio = Input Speed (rpm) \/ Output Speed (rpm)<\/strong>
\nExample: Input 1,450 rpm \/ Output 725 rpm = Ratio 2:1<\/span><\/div>\n

The ratio also determines torque multiplication. Output torque equals input torque multiplied by the ratio (minus efficiency losses). A 3:1 ratio gearbox receiving 100 N.m at the input delivers approximately 282 N.m at the output (100 x 3 x 0.94 efficiency).<\/p>\n

Standard Ever Power spiral bevel gearboxes<\/strong> are available in four ratios: 1:1, 1.5:1, 2:1, and 3:1. All four ratios share the same housing envelope within each size series \u2014 simplifying spare parts management and machine design.<\/p>\n

2. Ratio Overview: Output Speed and Torque at 1,450 rpm Input<\/h2>\n
\n\n\n\n\n\n\n\n\n
Ratio<\/th>\nOutput Speed (rpm)<\/th>\nTorque Multiplication<\/th>\nEfficiency<\/th>\nPrimary Use<\/th>\n<\/tr>\n<\/thead>\n
1:1<\/td>\n1,450 rpm<\/td>\n1x (direction change only)<\/td>\n96%<\/td>\nSteering boxes, PTO drives, machine tool shafts<\/td>\n<\/tr>\n
1.5:1<\/td>\n967 rpm<\/td>\n1.43x<\/td>\n95.5%<\/td>\nFan drives, cooling towers, grain elevators<\/td>\n<\/tr>\n
2:1<\/td>\n725 rpm<\/td>\n1.9x<\/td>\n95%<\/td>\nConveyors, mixers, agitators, packaging lines<\/td>\n<\/tr>\n
3:1<\/td>\n483 rpm<\/td>\n2.82x<\/td>\n94%<\/td>\nSlow conveyors, kilns, screw drives, heavy mixers<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

3. The 1:1 Ratio: Direction Change, Not Speed Change<\/h2>\n

The 1:1 ratio is the most misunderstood configuration in the spiral bevel gearbox range. Engineers occasionally ask why a gearbox is needed at 1:1 \u2014 if the speed does not change, surely a simple coupling would do? The answer is that 1:1 spiral bevel gearboxes perform a function a coupling cannot: they change the direction of the drive shaft by 90 degrees.<\/p>\n

At 1:1, the output shaft rotates at exactly the same speed as the input shaft. Efficiency peaks at 96% because both gears have the same tooth count \u2014 the gear mesh geometry is perfectly symmetrical and transmission error is minimised. This is why 1:1 units are preferred for:<\/p>\n