How beginners can quickly master the selection skills of SMR series shaft mounted reducers

Novices can quickly master the selection of SMR shaft mounted reducers, with three key steps: constant speed ratio → torque calculation (with working condition safety factor) → verification of installation and environment; Prioritize torque/speed ratio/hollow shaft aperture, don't just focus on motor power.

1、 Understand the basic characteristics of SMR first (a must read for beginners)

SMR is a hollow shaft mounted helical gear reducer, which is directly mounted on the driven shaft and fixed by a torsion arm, without the need for a foundation. It has the advantages of simple installation, small space, and low cost.

Structure: single-stage/two-stage helical gears, high efficiency (single-stage ≈ 98%), low noise

Speed ratio: single-stage 5/13/20; Double level 25/65/100

Output: Hollow shaft (optional solid shaft), compatible with ISO standard shaft diameter

Core advantages: No coupling, no base, adjustable belt tension

2、 5-step quick selection (beginners can follow it directly)

Step 1: Determine the speed ratio i (speed matching)

Formula: i=Motor speed n ₁ ÷ Equipment required output speed n ₂

Common motors: 4-pole (1500rpm), 6-pole (1000rpm)

SMR standard speed ratio:

Single level: 5, 13, 20 (output 300/115)/ 75rpm@1500rpm ）

Dual level: 25, 65, 100 (output 60/23)/ 15rpm@1500rpm ）

Example: Motor 1500rpm, 50rpm → i=30, choose two-stage 25 (near) or 65 (slow).

Step 2: Calculate the load torque T (most importantly, don't just look at power)

Formula: T (N · m)=9550 × P (kW) ÷ n ₂ (rpm) × operating condition safety factor S

Safety factor S (mandatory, based on impact and daily operating hours):

Stable (conveyor, fan, ≤ 10h/day): 1.2-1.5

Medium (mixer, pump, ≤ 10h/day): 1.5-2.0

Strong impact (crusher, frequent start stop,>10h/day): 2.0-3.0

Requirement: The rated torque of the reducer should be ≥ the calculated torque T, and the peak torque should be ≥ 2 times the rated torque (to cope with starting impact).

Step 3: Select the aircraft seat number (check the table by torque/power)

SMR machine base number: SMR30/40/50/60/70/80/90, the larger the torque, the greater the torque.

Quick comparison (1500rpm motor, single-stage/two-stage):

Novice rule: Calculate torque within the range of 70% -90% of the rated torque of the machine base, with the longest lifespan and less susceptibility to damage.

Step 4: Check the hollow shaft aperture (must match during installation)

SMR hollow shaft standard aperture (mm):

SMR30：30

SMR40：40

SMR50：50

SMR60：60

SMR70：70