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Taking into account the fact that the efficiency is determined as ratio of the output power to the input one
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In general, the efficiency of the drive is determined as a product of efficiencies of all kinematic pairs and links where the input power is lost.
h=h1× h2× …× hn ,
In this case
h = hhsg × hcd× hc × hb2,
where hbd is the efficiency of the belt drive;
hhsg is the efficiency of the helical spur gearing;
hc is the efficiency of the coupling;
hb takes into account losses in one pair of bearings.
The magnitudes of all efficiencies are given in table 1.1.
Let us assume that hcd = 0.96, hhsg= 0.97, hc = 0.996, hb= 0.99. Then
h = 0.96 × 0.97 × 0.996 × 0.993 = 0.899.
Mind that the magnitude of the total efficiency must be rounded off to thousands.
Table 1.1
Efficiencies of gearings
| Name | Efficiency | |
| Closed drive | Opened drive | |
| Gearings: - straight spur gears - helical spur gears - bevel gears Worm gearing: -one thread worm -two thread worm -four thread worm Belt drives: - flat belt drive - V-belt drive - toothed belt drive Chain drives: - roller chain - toothed chain Couplings: - with rubber bushed studs - flexible coupling - rigid coupling Bearings: - rolling bearings - sliding bearings | 0, 98 - 0, 99 0, 97 - 0, 98 0, 96 - 0, 98 0, 7 - 0, 75 0, 75 - 0, 82 0, 82 - 0, 92 0, 996 0, 985 - 0, 995 0, 99 - 0, 995 0, 98 - 0, 985 | 0, 94 - 0, 96 0, 94 - 0, 95 0, 92 - 0, 94 0, 96 - 0, 98 0, 95 - 0, 97 0, 94 - 0, 97 0, 94 - 0, 96 0, 96 - 0, 97 |
1.2. Determine the output and input power.
Taking into account the fact that the efficiency is determined as ratio of the output power to the input one
h= 
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