Ratings Helical Gearbox

 pdf download  Dimension Details

pdf download  Capacity Details

Horse Power Ratings AGNEE Helical Gear Boxes

SELECTION PROCEDURE
Gearbox Selection for Horizontal Units

1. Select Gearbox Type

1.1 Parallel Shafts (helical) or right angle drive (bevel/helical), foot mount, shaft mount with or without foot.

1.2 Calculate gearbox ratio = Input Speed/ Output speed

2. Select Gearbox Size from Mechanical Capacity

2.1 Determine type of load from table uniform, moderate shock or heavy shock).

2.2 Determine mechanical service factor from table 1

2.3 Calculate the required mechanical power capacity (Pm )
(Pm ) = absorbed power (kW) x mechanical service factor

2.4 Select gearbox size from rating tables.
Pm must be equal to or less than the mechanical rating of the gearbox.

3. Thermal Rating Check
3.1 Thermal ratings are given for the following four cases :
Gearbox without additional cooling.
Gearbox fitted with fan.
Gearbox fitted with cooling water coil.
Gearbox fitted with fan and coil.

3.2 Determine the thermal service factor from table 2

3.3 Calculate the required thermal power capacity (Pt)
(Pt ) = absorbed power (kW) ÷ thermal service factor.

3.4 Specify the type of cooling required by referring to thermal rating tables.

Pt must be equal to or less than the thermal capacity of the gearbox

Additional Catalogue   Information

1. Gearbox overload capacity at start.
2.5 x mechanical rating, 5 times per day or,
2 x mechanical rating, 5 times per hour.

2. Intermittent duty.
Higher power than catalogue mechanical ratings can be transmitted on very intermittent operation within the finite life of the gears. Consult us with specific application details.

 Table 1: Mechanical Service Factors (Horizontal & Vertical)

Prime Mover Duration of  service Load Classifications-Driven Machine
Hrs. Per Day Uniform Moderate Shock Heavy Shock
ELECTRIC MOTOR, Steam Turbines Under 3
3 to 10
Over 10		 0.80
1.00
1.25		 1.00
1.25
1.50		 1.50
1.75
2.00
Multi-Cylinder Internal Combustion
Engine		 Under 3
3 to 10
Over 10		 1.00
1.25
1.50		 1.25
1.50
1.75		 1.75
2.00
2.25
 
Single Cylinder Internal Combustion
Engine		 Under 3
3 to 10
Over 10		 1.25
1.50
1.75		 1.50
1.75
2.00		 2.00
2.25
2.50
 
Table 2 : Thermal Service Factors (Horizontal & Vertical) for ambient temperature and duration of operation.
 
Type Of Cooling   Ambient Temperature Running Time in Hour
oC 100% 80% 60% 40% 20%
Gear Boxes without additional Cooling 10 1.12 1.34 1.57 1.79 2.05
20 1.00 1.20 1.40 1.60 1.80
30 0.88 1.06 1.23 1.41 1.58
40 0.75 0.9 1.05 1.20 1.35
50 0.63 0.76 0.88 1.01 1.13
Gear Boxes with Fan 10 1.15 1.38 1.61 1.84 2.07
20 1.00 1.20 1.40 1.60 1.80
30 0.09 1.08 1.26 1.44 1.62
40 0.80 1.96 1.12 1.29 1.44
50 0.70 0.84 0.98 1.12 1.26
 
Gear Boxes with Cooling Coil (1) 10 1.10 1.32 1.54 1.76 1.98
20 1.00 1.20 1.40 1.60 1.80
30 0.09 1.08 1.26 1.44 1.62
40 0.85 1.02 1.19 1.36 1.53
50 0.80 0.96 1.12 1.29 1.44
Gear Boxes with Fan & Cooling Coil (1) 10 1.12 1.34 1.57 1.79 2.05
20 1.00 1.20 1.40 1.60 1.80
30 0.92 1.10 1.29 1.47 1.66
40 0.83 1.0 1.16 1.33 1.50
50 0.78 0.94 1.09 1.25 1.40

(1) Based on Cooling -Water Temperature 20 C.

HOW TO ORDER, Selection Example

How to order-Information required when ordering standard gear units

 Prime Mover
 1. Type – electric motor or engine, for example 4 cylinder internal combustion engine
2. Power rating in kW
3. Output speed. If variable, indicate speed range and frequency of variable.
4. Dimensions of prime mover.
 Driven Machine
1. Type, for example, kiln, conveyor, etc.
2. Power rating in kW
3. Speed
4. Service – hours per day, running time in any hour, details of reversals if applicable, type of loading, ambient temperature, etc.

Gear Unit
1.Type, for example, H2.
2.Size, for example, 315.
3. Ratio
4. Shaft handling. Refer to dimension pages and quote reference.
5. Direction of rotation (for units with right angle shafts refer to handling diagrams on dimension pages). If holdback arrangement is to be fitted, please indicate the direction of rotation of low speed shaft looking towards it.

 
 Shaft Connections
1. Couplings Quote shaft diameters with tolerances or coupling bores.
2. Details of overhung loads, including diameter and type of sheave, sprocket or pinion and any thrust loads.

Shaft mounted units for High Inertia Drive
When used on Traverse drives with inertia driven loads, e.g. crane drives (slewing, long travel and cross travel) bogie drives and selected high inertia load roller table drives, it is recommended that shaft mounted units should be fitted with shock absorbing Torque Arms. Consult us with specific application details.
Example 1
A foot mounted parallel shaft speed reducer is to be directly coupled to a 750 kW, 1500 rpm motor. The output shaft is to rotate at 365 rpm and is coupled to a large industrial fan absorbs 725 kW on 24 hours/day service. The maximum ambient temperature is 300C.

Selection

1. Gearbox Type
1.1 Parallel shaft type is specified – type H.
1.2 Ratio =1500÷365
=4.11, type H1 (single reduction)
2. Mechanical Capacity
2.1 From table 3 on previous page  the application is moderate shock.
2.2 From table 1 on page 3 the service factor is 1.5.
2.3 The required mechanical capacity = 1.5 x 725 = 1088 kW
2.4 Under mechanical ratings a unit size 315, nominal ratio 4.13, has a capacity of 1293 kW
3. Thermal Rating Check
3.1 From table 2 on previous page  the thermal service factor for 300C ambient temperature and 100% running time is 0.9 for a unit with fan cooling (reference to the thermal ratings shows that at least fan cooling is required.)
3.2 The required thermal capacity = 725 – 0.9 = 806.
3.3 Under thermal ratings, fan cooled, a size 315 has a capacity of 918 kW at 1500 rpm, ratio 4.15
4. Check that the exact ratio.
5. Order a gearbox type H1 – 315 exact ratio 4.15 with cooling fans fitted.
Example 2
A shaft mounted gear unit right angle shafts is required to drive a belt conveyor running 24 hours/day at 80 rpm. The unit must have feet for the attachment of a motor mounting baseplate. The motor is 500 kW at 1500 rpm and the absorbed power at the conveyor headshaft is 465 kW. The ambient temperature on site is 200 C.

Selection

1. Gearbox Type
1.1 Foot shaft mounted unit with right angle shafts.
1.2 Ratio = 1500÷80 = 18.8, type B2SF could be used
2. Mechanical Capacity
2.1 From table 3 on page 10 the application is uniform load.
2.2 From table 1 on page 3 the service factor is 1.25
2.3 The required mechanical capacity = 1.25 x 465 = 581 kW
2.4 Under mechanical ratings a unit size B3SF – 400, nominal ratio 18.9, has a capacity of 620 kW. The double reduction type B2SF – 400 ratio 18.9 has insufficient mechanical capacity.
3. Thermal Rating Check
3.1 From table 2 on previous page  the thermal service factor for 20º C. ambient temperature and 100% running time is 1.0
3.2 The required thermal capacity = 465÷1.0 = 465 kW.
3.3 Under thermal ratings, fan cooled, a size 400 at 1500 rpm has a capacity of 484kW
4. Check that the exact ratio.
5. Order a gearbox type B3SF – 400, exact ratio with cooling fans fitted.

OVERHUNG LOADS / AXIAL THRUST LOADS – HORIZONTAL UNITS

Whenever a sprocket, gear, sheave or pulley is mounted on the shaft, a calculation should be made to determine the overhung load in kN on the shaft, using the formula :

p = kW x 9545 x K ÷ N x R
Where P = equivalent overhung load in kN,
kW = power carried by the shaft,
N = rpm of the shaft
R = pitch radius of sprocket, pinion,sheave or pulley (mm).
Overhung member  K Factor
Sprocket for chain 1
Spur gear 1.25
V belt sheave 1.5
Flat belt pulley 3.0

Notes :
1. Values are calculated for the most unfavourable direction of rotation. Consult us with specific application details.
2. Overhung load values are for loads applied midway along shaft extension.
3. For overhung load and axial thrust values for large sizes consult us.

 

 

 

 

 
Table 4 : Permissible Overhung Load on Low Speed Shaft (kN)  (Horizontal Units)
Direction
of
Load		 Output
Speed
(rpm)		 Types H2-H3-B2-B3
Unit Size
200 225 250 280 315 355 400 450
1 315 35 42 47 56 78 100 100 172
200 40 48 57 68 87 118 126 190
125 48 55 62 85 103 132 150 228
80 52 68 78 97 130 162 190 280
50 52 68 90 126 148 182 228 320
31.5≥ 52 68 90 126 148 182 230 320
2 315 35 42 47 56 78 100 109 172
200 40 48 62 85 87 118 126 190
125≥ 41 48 62 85 99 120 150 215
3 315≥ 18 23 30 42 49 61 78 107
Table 5 : Permissible Overhung Load High Speed Shaft at 1500 rpm(kN)  (Horizontal Units)
Type of
Unit		 Unit Size
200 225 250 280 315 355 400 450
H2-H2S-H2SF 8.45 10.5 13.0 19.5 26.5 32.2 38.7 45.8
H3-H3S-H3SF 3.03 4.58 6.45 8.4 10.5 13.0 20.0 28.9
B2-B2S-B2SF 12.0 15.6 19.6 25.4 30.6 36.0 41.3 49.8
B3-B3S-B3SF 3.03 7.12 8.90 12.0 15.6 19.6 25.4 30.6
Table 6 : Permissible Axial Thrust on Low Speed Shaft (kN)
(Horizontal Units)
 
Output
Speed
rpm		 Type H2-H3-B2-B3
200 225 250 280 315 355 400 450
315 12.0 12.5 13.4 11.8 18.3 30.3 28.8 53.4
200 13.4 14.2 15.2 13.3 20.8 34.3 32.6 60.5
125 17.1 17.3 18.0 18.4 25.3 40.0 40.9 70.8
80 18.2 20.5 21.8 23.8 35.6 63.6 55.4 80.85
50 19.4 25.8 25.3 32.1 43.5 66.3 68.5 94.3
31.5 and
below		 19.4 25.8 25.3 34.3 55.6 66.3 88.6 94.3