Worm Gears Durand Range


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Worm Gears
Durand® Range
www.cmdgears.com

Standard worm gear reducers
NOISELESS
The worm gears operate with a high sliding speed, associated with a large gear overlapping ratio, which makes this type of gear the most silent gear transmission.
STURDY
The high stiffness of the housing, together with the use of largely sized quality components provides the users with the most robust generation of worm gear units. CMD Durand gear units are designed to transmit high torques within limited room.

COMPACTNESS
The compactness of the CMD Durand gear units is an advantage for
many applications. They have been designed with the aim at reducing
the overall dimensions: • right angle arrangement of the shafts
• hollow shaft design • large ratios within a compact volume.

EASY MAINTENANCE
The simple design, associated with easy access to all components reduce drastically the maintenance costs. CMD can specify the selection of lubricant together with maintenance recommendations.

ACCURATE
Nowadays, gear cutting and grinding machines allow the production of high accuracy gears having very low pitch deviation and accurate profile. Great positioning is therefore
achievable for applications such as robotics, machine tools,
printing machine, etc.
PROCESS MONITORING
CMD has developed a simple system which monitors the absorbed power of the driven
machine on a continuous basis.

1

Summary
Generalities and Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . p. 3-4 Reducer type selection according to gear ratio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . p. 5 N range and JUMBOFLEX – Selection method sizes from 160 to 1250 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . p. 6 Service factor – Classification of machines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . p. 7 Reversibility and self-locking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . p. 8 Selection method - Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . p. 9 Sizes 160 F/C to 500 F/C – Mechanical rating and thermal capacity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . p. 11-13 Overall dimensions sizes from 160 to 500 F/C Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . p. 14 Multi reduction reducers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . p. 15 JUMBOFLEX – Mechanical rating and thermal capacity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . p. 17-19 JUMBOFLEX overall dimension F Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . p. 20 JUMBOFLEX overall dimension MH1 Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . p. 21 JUMBOFLEX overall dimension MH2 Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . p. 22 Torque arm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . p. 24 Base kits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . p. 25 Dynamometric shock absorbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . p. 26 Hollow shaft with shrink rim assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . p. 27 Gear motors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . p. 28 Maximum admissible torque Co . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . p. 29 Mounting – Installation – Lubrication – Commissioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . p. 30 Reducers – Requested information for inquiries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . p. 31 Data and application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . p. 33-37 Worm gear sets – Requested information for inquiries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . p. 38 Main machine tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . p. 39 Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . p. 41-52
2

Generalities and Design
The CMD Durand technology is constantly evolving and being optimised, thanks to several decades of experience in cooperation with the end users. CMD is considered as a specialist for medium and large size of worm gears and offers a wide range of worm gearboxes that complies with very demanding industrial applications: metal, sugar, cement, waste recycling, environment, material handling, machine tools industries… Whenever the standard range is not adapted, CMD can modify the standard design or provide a custom design to comply with specific requirements: high accuracy, high torques, specific dimensions, specific kinematic design… This catalogue describes in details the N series, from size 160 to 500, the type F or FN (hollow output shaft) and the type C or FNC (solid output shaft) as well as the range of large reducers JUMBOFLEX sizes 550 to 1250. Large reduction ratios are made possible by combining several reducers. Various accessories such as reaction torque arms, temperature sensors, torque and load sensors, couplings… are available to adapt the standard units to customer’s requirements. Method of selection, mechanical and thermal nominal ratings are given for N series reducers. For customers that will to integrate worm gear set in their machine, we recommend that selection is made using catalogue center distance and ratio. However, CMD also manufacture specific centre distance and gear ratio in order to meet specific requirements – please consult CMD.

GEARS
CMD Durand as a specialist of worm gears, has selected the A profile (DIN3975) for optimising the length of contact, Hertz contact pressures and lubrication.
The torque rating is calculated in accordance with BS721-Durand standard.
Thermal rating is calculated in consideration of the design parameters and the performances of lubricants that have been tested on CMD Durand test bench.
The worm shaft is made of alloyed steel forgings, its threads are case carburised and ground on CNC machines of the latest generation, warranting very high accuracy.
The worm wheel teeth are made of high mechanical properties and low friction bronze.
Gear contact pattern is simulated on computer in order to optimise the oil film thickness and the adaptation of the teeth surfaces under load from the very first running hours.
HOUSING
The very compact housings are made of high quality cast iron GSL, GJS or cast steel GE 280 for specific applications.
Robust design allows the unit to withstand high internal and external loads. The internal arrangement of the housing insures automatic lubrication of bearings.
The housing allows multiple position mounting and accommodates various optional items.

BEARINGS
CMD Durand has a long experience in using roller bearings that withstand the thrust loads generated by worm gears. These bearings are also selected to withstand the external loads (radial, axial…) that vary from one application to another. The selection of bearings and their mounting arrangement insure optimal gear meshing.
LUBRICATION
CMD Durand has tested both test bench and at site a large number of synthetic and mineral oils which results have been used to determine the ratings given in this catalogue. CMD Durand gear units that are lubricated by synthetic Polyglycol oils offer the highest performances in terms of transmitted power, efficiency and durability. For most of applications, splashing lubrication is sufficient enough. For applications which require oil circulation and injection, CMD provides a complete lubrication system inclusive of pumps, monitoring and accessories. Because of the running position of the reducer and due to low speed operation, bearings are sometimes lubricated by EP grease.
Note: CMD Durand provides general or specific lubrication instructions.

3

Generalities and Design

SEALING
Joint sealants compatible with Polyglycol synthetic oils are used for sealing joint faces. The sealing of the rotating parts is performed by standard Nitrile or Viton seal rings.
COUPLINGS
CMD Durand worm gearboxes can be fitted with flexible grid couplings Winflex 9000 and/or Flexident crown gear couplings. CMD catalogues for couplings are available upon request.

ACCESSORIES AND OPTIONS
Numerous accessories and optional items can be supplied to fit our CMD Durand reducers, such as:
• special hollow shaft • double output shaft with standard or custom
dimension • shrink disk arrangement for hollow shaft • reaction torque arm • shock absorber (with safety switch) • torque, temperature sensors etc… • backstop, free wheel • lubrication system with accessories • mechanical fan, heat exchanger • flange for motors • special centre distance and gear ratios

Winflex

Flexident
QUALITY CONTROL
All our products benefit from the following permanent checking:
• raw material / bought in material inspection • incoming goods inspection • manufacturing inspections • gear teeth contact pattern inspection • final dimensional inspection • final inspection with running test • protective packing in accordance
with ISO 9001:2000
4

CETIM Photo - C. Barret

Reducer type selection according to gear ratio u Single unit or multi reduction units

u Worm reducer (1)

Multi reduction

worm reducers (2)

5

N range

7.5

F/C Type

10

Jumboflex

12.5

15

20

25

30

N range

40

u = from 5 to 60

F/C Type

50

Overall dimensions

Jumboflex

60 refer to page 14 and 20

MH reducer (3)

Multi reduction worm reducers + MH (4)

N range MHF1, MHC1 Type
Jumboflex

80

u = from 15 to 230

N range

F/C Type

180

Overall dimensions

Jumboflex

refer to page 21 and 22

225

MHF2, MHC2 Type

230

u = from 25 to 3600

Jumboflex

Primary MH1

Overall dimensions

refer to page 15

u = from 50 to 800

u = from 80 to 18000

800

3600
10800
48000
Reducers (1) to (4): available sizes from 160 to 1250, option for gear motors For selection of Reducers (2) (3) (4) consult CMD Reversibility and self-locking class refer to page 8

Primary MH2 u = from 225 to 48000
5

Worm gear units N range and JUMBOFLEX from sizes 160 to 1250

1. Selection of the gear ratio
u= High Speed shaft rotation speed, N1 (HS) / Low Speed shaft rotation speed, N2 (LS). The rating selection tables, pages 11-13 and 17-19, provide the standard gear ratios.
u = N1 / N2
Note: for final selection of gear ratio, it is required to check that the reversibility condition is in conformity with the application page 8.
2. Selection of the service factor SF
The service factor SF is determined according to the application and the service conditions. For a large number of application, SF is calculated on the tables provided on page 7.
SF = FA x FH x FL x FD
3. Calculation of the required torque rating
The required torque rating Mts equals the transmitted torque M2 multiplied by the service factor SF:
Mts = M2 x SF
4. Reducer size selection
Select in the mechanical ratings table the standard ratio which is the closest to the calculated ratio obtained in 1. On the line corresponding to the chosen gear ratio and to the input speed N1, select the size of the reducer having a torque rating Mt2 equals to, or higher than the calculated torque (paragraph 3). Check that the following condition is fulfilled:
Mt2 ≥ Mts

5. Checking of reducer thermal power
The thermal power of the running reducer equals the absorbed power time series of factors provided page 7.
Pths = Pa x FT x FM x FP
Allowable thermal power Pth is given on the lower table of the page corresponding to selected reducer page 4. On the line corresponding to the chosen gear ratio u and to the input speed N1, check the value of Pth (without fan), Pthv (with fan) or Pthc (with lubrication circuit), and verify that:
Pth ≥ Pths Pthv ≥ Pths (N range) Pthc ≥ Pths (Jumboflex)
6. Checking of maximum permissible torque
The maximum permissible peak torque Co at the output shaft of the reducer, inclusive of inertias, must be higher than the maximum peak torque of the application M2maxi.
Co > M2maxi
Note: In the specific case of power transmission using several reducers simultaneously, it is recommended to apply a correction factor Fr that takes into account the unequal load sharing on each reducer (example: travel drive, cranes…). Fr = 1.15 to 1.3 in case of drive with 2 to 4 reducers. Fr = 1.3 to 1.6 in case of drive with more than 4 reducers.

6

Service factor - Classification of machines

SERVICE FACTOR SF FOR MECHANICAL RATING SELECTION SF = FA x FH x FL x FD

Service conditions
Uniform U

Driven machines
Screw conveyors – Belt or bucket conveyors with uniform loading – Light elevators – Travel drive for machine tools – Shearing press driving gears – Sheet cutting drives – Generators – Packing machines – Mixers for light liquids or homogeneous materials – Light centrifugal pumps – Fans.

Application factor FA

Daily duty cycles

Hours U

L

M

H

3≤h<8 0.8

1

1.25 1.50

8≤h≤12 1

1.25 1.50 1.75

h>12 1.25 1.50 1.75

2

Light shocks L

Calanders – Heavy centrifugal machines – Main drives for machine tools – Belt or bucket conveyors with nonuniform loading, for instance mixed materials – Heavy elevators – Cranes slewing drives – Extruders – Rotary kilns – Strip mills (continuous mill for zinc plates, aluminium angle bars and plates) – Mixers for heavy liquids or non-homogeneous materials – Centrifugal pumps – Processing pumps – Piston pumps – Industrial and mining fans.

Medium shocks M

Light ball mills – Lifting gears – Rubber extruders – Blooming mills – Wood processing machines (multiple blade sawing machines, rough turning machines) – Intermittent operation mixers for rubber and plastic materials – Single cylinder pumps.

Heavy shocks H

Roller mills – Heavy vertical mills – Pellet wheel drives – Mining screens – Quarry and mining crushers – Dredges – Bucket elevators – Heavy plates shearing machines – Peeling machines – Cold rolling mills – Heavy drilling machines – Steel processing machines – Heavy rubber mixers – Heavy processing pumps – Brick extruders – Bucket wheels.

Life factor FH

Required

Required

service life FH service life FH

8000 h 0.70 50000 h 1.25

10000 h 0.75 75000 h 1.43

25000 h

1

100000 h 1.57

Lubrificant factor FL

Synthetic oil PolyGlycol

1

Mineral oil EP

1.25

Starting condition factor FD

Number of starts or reversings per hour

Starts/h 10 100 200 300 400

FD

1 1.1 1.15 1.2 1.3

THERMAL RATING FACTORS

Ambient temperature factor FT
is related to the ambient temperature and type of lubricant

Ambient temp. °C
Oil type SPynotlyhGeltyiccoolil FT Mineral oil EP FT

0 10 20 30 40 50 0.78 0.87 1 1.16 1.40 1.75
1 1.14 1.33 1.60 2 2.70

Loading cycle factor FM
is related to the ratio: % = (total operation time under load during one cycle /
total cycle time) x 100

%

100

80

60

40

20

FM

1

0.90

0.80

0.70

0.60

Operating position factor FP
is related to the position of the high speed shaft and the output shaft relatively to the ground.

Reducer
position S

FP

1

G

D

I

V

1 1 1.15 1.25

7

Reversibility and self-locking

Operating as a speed reducer:
The worm shaft is driving the wheel connected to the driven machine. The power is transmitted by the worm shaft to the wheel.
Operating as speed increaser:
The worm wheel is driving and transmit power to the worm shaft.
Reversibility:
This property is applicable for both directions of rotation. Operation as speed increaser in this case is possible. Reversibility allows the driven load to become the driving element (for instance, slowing down an heavy inertia machine).

Self-locking:
This property is applicable for both direction of rotation. Operation as speed increaser in this case is impossible. Self locking prevents the driven load from becoming a driving element: this safety condition is required for lifting application (for instance).
In stopped condition the self-locking is called “static self-locking” whereas in running conditions is called “dynamic self-locking”.
In case of dynamic self-locking, if the driven load becomes the driving element, the reducer will stop running, immediately or after a very short while, depending on the resisting torques in the drive chain. The complete dynamic self-locking condition is practically never reached, unless in the specific case of high ratios and speeds close to zero.

Reversibility class
The table below is to be used for the selection of the gear ratio of the reducer which is required to fulfil the reversibility or self-locking condition. For specific cases, please consult CMD.

Reversibility class table

Class #

Definition

1 Full static and dynamic reversibility

2 Static and dynamic reversibility Fast reverse effect
Poor static reversibility 3 Dynamic reversibility
Fast reverse effect under vibrations
Static self-locking 4 Fast reverse effect under vibrations
Poor dynamic reversibility (*)
Static self-locking 5 Fast reverse effect under vibrations
Very poor dynamic reversibility (*)
(*) relative to worm shaft rotation (low speed)

Maximum thread angle for each reversibility class, depending on reduction ratio and centre distance.

Class u / size 160

200

250

315

400

450

500

1 5 39 41 41

7.5

29

31

31

34

41

39

41

10

23

24

26

28

31

32

31

2 12.5 19 21 20 23 26 29 27

15

16

17

16

20

22

24

24

20

12

13

13

15

17

18

18

3 25 9

30

8

9

10

12

14

14

14

9

8

10

11

13

12

4

40

6

6

7

8

8

9

9

5 50 4 5 5 6 7 8 8

60

4

4

4

5

6

6

7

♦ for larger sizes, consult CMD

Note: for standard applications where reversibility is required, we recommend classes 1 and 2. When full static self-locking is required, select classes 4 and 5 and install a safety brake. For multi reduction reducers, the reversibility ability of the whole drive is achieved if all reducers are reversible. The self-locking ability is achieved if the larger unit is self-locking (preferably, the smaller units should be self-locking as well).

Efficiency
For a given ratio, the efficiency increases with the size of the gearbox, the sliding velocity (worm shaft speed) and the lead angle. Polyglycol synthetic oil also provides optimum efficiency.
The efficiency ηr of the reducer lubricated with synthetic polyglycol lubricant can be estimated as follows:

ηR = Mt2.N2
9550.P1

Mt2 output torque (N.m) N2 output shaft rotation (rpm) P1 input power on worm shaft (kW)

8

Selection method – Example of selection

Example:
• application: conveyor drive • 24h continuous duty, uniform load • ambient temperature 30°C • motor rating 55 kW @ 1500 rpm • output shaft rotation N2 = 47 rpm • absorbed power Pa = 52 kW @ 1480 rpm • efficiency η = 0.93 • output torque M2 = 9830 Nm • required life 50000 hrs • maximum output peak torque
M2 maxi = 25000 Nm • operating position: S (the worm shaft
is horizontal, above the worm wheel) • lubricant: Polyglycol synthetic oil PG
1) Gear ratio u
u = N1 / N2 = 1480 / 47 = 31.5 Select exact ratio 30 refer to page 12 (Standard gear ratio refer to page 29)
2) Service factor SF
SF = FA x FH x FL x FD FA = 1.25 FH = 1.25 FL = 1 FD = 1 SF = 1.25 x 1.25 x 1 x 1 = 1.56
3) Selection torque
Mts = M2 x SF = 9830 x 1.56 = 15 335 Nm

4) Sizing of the reducer
Select the size of the reducer from the mechanical power ratings table, on pages 11 to 13. For u = 30 and N1= 1500, the size 315 is selected, on page 12. The condition Mt2>MTs is fulfilled.
5) Thermal power rating
The required thermal rating is Pths = Pa x FT x FM x FP Facteurs FT = 1.16 FM = 1 FP =1 Pths = 52 x 1.16 x 1 x 1 = 60.3 kW The power rating is indicated in the table on the bottom of page 12. The thermal rating for gearbox 315, ratio 30 is Pthv = 62 kW @ 1500 rpm with fan. The condition Pthv>Pths is fulfilled.
6) Verification of the maximum peak torque on the output shaft: Co
Refer to Co table on page 29: for unit size 315 and gear ratio 30, the maximum admissible peak torque Co is 51130 Nm which is higher than the required 25000 Nm. The condition Co>M2maxi is fulfilled.

9

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Worm Gears Durand Range