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Analysis of the bending cycle distribution of 1- to 8-part electric hoists ©

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Page 1: Casar Bending Cycle

Analysis of the bending cycle distribution of 1- to 8-part electric hoists

Analysis of the bending cycle distributionof 1- to 8-part electric hoists

©

Page 2: Casar Bending Cycle

Analysis of the bending cycle distribution of 1- to 8-part electric hoists

Page 3: Casar Bending Cycle

Analysis of the bending cycle distribution of 1- to 8-part electric hoists

Analysis of the bending cycle distribution of 1- to 8-part electric hoists

1. Introduction .................................................................... Page 2

2. The single-part hoist ...................................................... Page 4

3. The 2-part hoist .............................................................. Page 6

4. The 3-part hoist .............................................................. Page 8

5. The 4-part hoist .............................................................. Page 10

6. The 5-part hoist .............................................................. Page 12

7. The 6-part hoist .............................................................. Page 14

8. The 7-part hoist .............................................................. Page 16

9. The 8-part hoist .............................................................. Page 18

10. Summary ........................................................................ Page 20

11. The right rope for electric hoists .................................... Page 23

by Dipl.-Ing. Roland Verreet

1

Page 4: Casar Bending Cycle

Analysis of the bending cycle distribution of 1- to 8-part electric hoists

1. Introduction

During the hoisting operation of a crane, not all sections of the hoist rope are subjected to the same number of bending cycles. Instead, the distribution of the bending cycles depends on the geometry of the reeving system and on the mode of operation of the crane.

The author has written a program which calculates and displays the distri-bution of the bending cycles along the rope length and the maximum number of bending cycles depending on the lifting height.

As an example of the possibilities of such software, the distribution of bending cycles of 1- to 8-part electric hoists, according to fi gure 1, will be analyzed in the following paper.

For all hoists, the distribution will be analyzed for lifting heights of 25%, 50%, 75% and 100% of the maximum possible lifting height. In addition, the distribution of bending cycles will be analyzed under the assumption that these four lifting heights will occur with the same frequency.

At the end, a proposal for an estimation of the maximum number of bend-ing cycles for different lifting heights will be presented.

Fig. 1: Schematic arrangements of the 1- to 8-part hoists

2

Page 5: Casar Bending Cycle

Analysis of the bending cycle distribution of 1- to 8-part electric hoists

Hoist 1

Hoist 2

Hoist 3

Hoist 4

Hoist 5

Hoist 7

Hoist 7

Hoist 8

No. of parts [-]

1

2

3

4

5

6

7

8

No. of sheaves [-]

0

1

2

3

4

5

6

7

Rope length [mm]

19000

35503

52005

68508

85011

101513

118016

134519

Fig. 2: Data of the analyzed hoists

Figure 2 shows the data of the 8 electric hoists. The rope diameter has been set to d = 16 mm, the sheave and drum diameters to D = 320 mm (= 20 x d). The maximum distances between the sheaves have been set to 16 m for all hoists, and the maximum lifting height to 15m. In addition, a reserve rope length on the drum (the “dead turns”) has been allowed for on all hoists.

In the following, the results of every one of the 8 hoists will be presented on two pages each. The results are shown as a function of the rope length, displayed as a percentage of the total rope length according to fi gure 2.

In the fi nal chapter some general conclusions are drawn.

3

Page 6: Casar Bending Cycle

Analysis of the bending cycle distribution of 1- to 8-part electric hoists

2. The single-part hoist

Figure 3 shows the maximum number of bending cycles for one full hoisting cycle (=1x lifting, 1 x lowering) as a function of the lifting height. Figure 5 (next page) shows the distribution of bending cycles as a function of the rope length (expressed in % of the total rope length) for one full hoisting cycle (=1 x lifting, 1 x lowering) for lifting heights of 25%, 50%, 75% and 100% of the maximum lifting height. Figure 4 shows the average number of bending cycles for a hoist which lifts the block to these four heights with the same frequency.

Fig. 3: Maximum number of cycles depending on the lifting height

Figure 4: Distribution of bending cycles per hoisting cycle if lifting heights of 25%, 50%, 75% and 100% of the maximum lifting height occur with the same frequency

Rope length from fix point [ % ]

No.

of

cycl

es p

er h

oist

ing

cycl

e [

- ]

0 5 10010 20 30 40 50 60 70 80 90

0,0

0,5

1,0

1,5

15 25 35 45 55 65 75 85 95

Lifting height25/50/75/100%

Lifting height [ % of the maximum lifting height ]

No.

of

cycl

es p

er h

oist

ing

cycl

e [

- ]

0 5 10010 20 30 40 50 60 70 80 9015 25 35 45 55 65 75 85 950

1

2

4

Page 7: Casar Bending Cycle

Analysis of the bending cycle distribution of 1- to 8-part electric hoists

Figure 5: Number of bending cycles depending on the rope length for lifting heights of 25%, 50%, 75% and 100% of the maximum lifting height (single-part hoist)

No.

of

bend

ing

cycl

es [

- ]

0 10010 20 30 40 50 60 70 80 90

Rope length from fix point [ % ]

5 15 25 35 45 55 65 75 85 95

0

1

2

Lifting height100%

No.

of

bend

ing

cycl

es [

- ]

0

1

2

Lifting height25%

No.

of

bend

ing

cycl

es [

- ]

0

1

2

Lifting height50%

No.

of

bend

ing

cycl

es [

- ]

0

1

2

Lifting height75%

5

Page 8: Casar Bending Cycle

Analysis of the bending cycle distribution of 1- to 8-part electric hoists

3. The 2-part hoist

Figure 6 shows the maximum number of bending cycles for one full hoisting cycle (=1 x lifting, 1 x lowering) as a function of the lifting height. Figure 8 (next page) shows the distribution of bending cycles as a function of the rope length (expressed in % of the total rope length) for one full hoisting cycle (=1 x lifting, 1 x lowering) for lifting heights of 25%, 50%, 75% and 100% of the maximum lifting height. Figure 7 shows the average number of bending cycles for a hoist which lifts the block to these four heights with the same frequency.

Fig. 6: Maximum number of cycles depending on the lifting height

Figure 7: Distribution of bending cycles per hoisting cycle if lifting heights of 25%, 50%, 75% and 100% of the maximum lifting height occur with the same frequency

0 10010 20 30 40 50 60 70 80 90

0,0

0,5

1,0

1,5

2,0

2,5

3,0

5 15 25 35 45 55 65 75 85 95

Rope length from fix point [ % ]

No.

of

cycl

es p

er h

oist

ing

cycl

e [

- ]

Lifting height25/50/75/100%

Lifting height [ % of the maximum lifting height ]

No.

of

cycl

es p

er h

oist

ing

cycl

e [

- ]

0 5 10010 20 30 40 50 60 70 80 9015 25 35 45 55 65 75 85 95

0

1

2

3

4

6

Page 9: Casar Bending Cycle

Analysis of the bending cycle distribution of 1- to 8-part electric hoists

Figure 8: Number of bending cycles depending on the rope length for lifting heights of 25%, 50%, 75% and 100% of the maximum lifting height (2-part hoist)

No.

of

bend

ing

cycl

es [

- ]

0 10010 20 30 40 50 60 70 80 90

Rope length from fix point [ % ]

5 15 25 35 45 55 65 75 85 95

0

1

2

3

4

Lifting height100%

No.

of

bend

ing

cycl

es [

- ]

0

1

2

3

4

Lifting height50%

No.

of

bend

ing

cycl

es [

- ]

0

1

2

3

4

Lifting height25%

No.

of

bend

ing

cycl

es [

- ]

0

1

2

3

4

Lifting height75%

7

Page 10: Casar Bending Cycle

Analysis of the bending cycle distribution of 1- to 8-part electric hoists

4. The 3-part hoist

Figure 9 shows the maximum number of bending cycles for one full hoisting cycle (=1 x lifting, 1 x lowering) as a function of the lifting height. Figure 11 (next page) shows the distribution of bending cycles as a function of the rope length (expressed in % of the total rope length) for one full hoisting cycle(=1 x lifting, 1 x lowering) for lifting heights of 25%, 50%, 75% and 100% of the maximum lifting height. Figure 10 shows the average number of bending cycles for a hoist which lifts the block to these four heights with the same frequency.

Fig. 9: Maximum number of cycles depending on the lifting height

Figure 10: Distribution of bending cycles per hoisting cycle if lifting heights of 25%, 50%, 75% and 100% of the maximum lifting height occur with the same frequency

Lifting height [ % of the maximum lifting height ]

No.

of

cycl

es p

er h

oist

ing

cycl

e [

- ]

0 5 10010 20 30 40 50 60 70 80 9015 25 35 45 55 65 75 85 95

0

1

2

3

4

5

6

0 10010 20 30 40 50 60 70 80 905 15 25 35 45 55 65 75 85 95

0,0

0,5

1,0

1,5

2,0

2,5

3,0

3,5

4,0

Rope length from fix point [ % ]

No.

of

cycl

es p

er h

oist

ing

cycl

e [

- ]

Lifting height25/50/75/100%

8

Page 11: Casar Bending Cycle

Analysis of the bending cycle distribution of 1- to 8-part electric hoists

Figure 11: Number of bending cycles depending on the rope length for lifting heights of 25%, 50%, 75% and 100% of the maximum lifting height (3-part hoist)

No.

of

bend

ing

cycl

es [

- ]

0 10010 20 30 40 50 60 70 80 90

Rope length from fix point [ % ]

5 15 25 35 45 55 65 75 85 95

0

1

2

3

4

5

6

Lifting height100%

No.

of

bend

ing

cycl

es [

- ]

0

1

2

3

4

5

6

Lifting height50%

No.

of

bend

ing

cycl

es [

- ]

0

1

2

3

4

5

6

Lifting height25%

No.

of

bend

ing

cycl

es [

- ]

0

1

2

3

4

5

6

Lifting height75%

9

Page 12: Casar Bending Cycle

Analysis of the bending cycle distribution of 1- to 8-part electric hoists

5. The 4-part hoist

Figure 12 shows the maximum number of bending cycles for one full hoisting cycle (=1 x lifting, 1 x lowering) as a function of the lifting height. Figure 14 (next page) shows the distribution of bending cycles as a function of the rope length (expressed in % of the total rope length) for one full hoisting cycle (= 1 x lifting, 1 x lowering) for lifting heights of 25%, 50%, 75% and 100% of the maximum lifting height. Figure 13 shows the average number of bending cycles for a hoist which lifts the block to these four heights with the same frequency.

Fig. 12: Maximum number of cycles depending on the lifting height

Figure 13: Distribution of bending cycles per hoisting cycle if lifting heights of 25%, 50%, 75% and 100% of the maximum lifting height occur with the same frequency

Lifting height [ % of the maximum lifting height ]

No.

of

cycl

es p

er h

oist

ing

cycl

e [

- ]

0 5 10010 20 30 40 50 60 70 80 9015 25 35 45 55 65 75 85 95

0

1

2

3

4

5

6

7

8

0 10010 20 30 40 50 60 70 80 905 15 25 35 45 55 65 75 85 95

0,00,51,01,52,02,53,03,54,04,55,0

Rope length from fix point [ % ]

No.

of

cycl

es p

er h

oist

ing

cycl

e [

- ]

Lifting height25/50/75/100%

10

Page 13: Casar Bending Cycle

Analysis of the bending cycle distribution of 1- to 8-part electric hoists

Figure 14: Number of bending cycles depending on the rope length for lifting heights of 25%, 50%, 75% and 100% of the maximum lifting height (4-part hoist)

No.

of

bend

ing

cycl

es [

- ]

0 10010 20 30 40 50 60 70 80 90

Rope length from fix point [ % ]

5 15 25 35 45 55 65 75 85 95

0

1

2

3

4

5

6

7

8

Lifting height100%

No.

of

bend

ing

cycl

es [

- ]

0

1

2

3

4

5

6

7

8

Lifting height25%

No.

of

bend

ing

cycl

es [

- ]

0

1

2

3

4

5

6

7

8

Lifting height50%

No.

of

bend

ing

cycl

es [

- ]

0

1

2

3

4

5

6

7

8

Lifting height75%

11

Page 14: Casar Bending Cycle

Analysis of the bending cycle distribution of 1- to 8-part electric hoists

6. The 5-part hoist

Figure 15 shows the maximum number of bending cycles for one full hoisting cycle (=1 x lifting, 1 x lowering) as a function of the lifting height. Figure 17 (next page) shows the distribution of bending cycles as a function of the rope length (expressed in % of the total rope length) for one full hoisting cycle (=1 x lifting, 1 x lowering) for lifting heights of 25%, 50%, 75% and 100% of the maximum lifting height. Figure 16 shows the average number of bending cycles for a hoist which lifts the block to these four heights with the same frequency.

Figure 15: Maximum number of cycles depending on the lifting height

Figure 16: Distribution of bending cycles per hoisting cycle if lifting heights of 25%, 50%, 75% and 100% of the maximum lifting height occur with the same frequency

Lifting height [ % of the maximum lifting height ]

No.

of

cycl

es p

er h

oist

ing

cycl

e [

- ]

0 5 10010 20 30 40 50 60 70 80 9015 25 35 45 55 65 75 85 95

0123456789

10

0 10010 20 30 40 50 60 70 80 905 15 25 35 45 55 65 75 85 95

0,0

1,0

2,0

3,0

4,0

5,0

6,0

Rope length from fix point [ % ]

No.

of

cycl

es p

er h

oist

ing

cycl

e [

- ]

Lifting height25/50/75/100%

12

Page 15: Casar Bending Cycle

Analysis of the bending cycle distribution of 1- to 8-part electric hoists

Figure 17: Number of bending cycles depending on the rope length for lifting heights of 25%, 50%, 75% and 100% of the maximum lifting height (5-part hoist)

No.

of

bend

ing

cycl

es [

- ]

0 10010 20 30 40 50 60 70 80 90

Rope length from fix point [ % ]

5 15 25 35 45 55 65 75 85 95

0123456789

10

Lifting height100%

No.

of

bend

ing

cycl

es [

- ]

0123456789

10

Lifting height25%

No.

of

bend

ing

cycl

es [

- ]

0123456789

10

Lifting height50%

No.

of

bend

ing

cycl

es [

- ]

0123456789

10

Lifting height75%

13

Page 16: Casar Bending Cycle

Analysis of the bending cycle distribution of 1- to 8-part electric hoists

7. The 6-part hoist

Figure 18 shows the maximum number of bending cycles for one full hoisting cycle (=1 x lifting, 1 x lowering) as a function of the lifting height. Figure 20 (next page) shows the distribution of bending cycles as a function of the rope length (expressed in % of the total rope length) for one full hoisting cycle(=1 x lifting, 1 x lowering) for lifting heights of 25%, 50%, 75% and 100% of the maximum lifting height. Figure 19 shows the average number of bending cycles for a hoist which lifts the block to these four heights with the same frequency.

Figure 18: Maximum number of cycles depending on the lifting height

Figure 19: Distribution of bending cycles per hoisting cycle if lifting heights of 25%, 50%, 75% and 100% of the maximum lifting height occur with the same frequency

Lifting height [ % of the maximum lifting height ]

No.

of

cycl

es p

er h

oist

ing

cycl

e [

- ]

0 5 10010 20 30 40 50 60 70 80 9015 25 35 45 55 65 75 85 95

0

2

4

6

8

10

12

0 10010 20 30 40 50 60 70 80 905 15 25 35 45 55 65 75 85 95

0,0

1,0

2,0

3,0

4,0

5,0

6,0

7,0

Rope length from fix point [ % ]

No.

of

cycl

es p

er h

oist

ing

cycl

e [

- ]

Lifting height25/50/75/100%

14

Page 17: Casar Bending Cycle

Analysis of the bending cycle distribution of 1- to 8-part electric hoists

Figure 20: Number of bending cycles depending on the rope length for lifting heights of 25%, 50%, 75% and 100% of the maximum lifting height (6-part hoist)

No.

of

bend

ing

cycl

es [

- ]

0

2

4

6

8

10

12

Lifting height75%

No.

of

bend

ing

cycl

es [

- ]

0 10010 20 30 40 50 60 70 80 90

Rope length from fix point [ % ]

5 15 25 35 45 55 65 75 85 95

0

2

4

6

8

10

12

Lifting height100%

No.

of

bend

ing

cycl

es [

- ]

0

2

4

6

8

10

12

Lifting height50%

No.

of

bend

ing

cycl

es [

- ]

0

2

4

6

8

10

12

Lifting height25%

15

Page 18: Casar Bending Cycle

Analysis of the bending cycle distribution of 1- to 8-part electric hoists

8. The 7-part hoist

Figure 21 shows the maximum number of bending cycles for one full hoisting cycle (=1 x lifting, 1 x lowering) as a function of the lifting height. Figure 23 (next page) shows the distribution of bending cycles as a function of the rope length (expressed in % of the total rope length) for one full hoisting cycle (=1 x lifting, 1 x lowering) for lifting heights of 25%, 50%, 75% and 100% of the maximum lifting height. Figure 22 shows the average number of bending cycles for a hoist which lifts the block to these four heights with the same frequency.

Figure 21: Maximum number of cycles depending on the lifting height

Figure 22: Distribution of bending cycles per hoisting cycle if lifting heights of 25%, 50%, 75% and 100% of the maximum lifting height occur with the same frequency

Lifting height [ % of the maximum lifting height ]

No.

of

cycl

es p

er h

oist

ing

cycl

e [

- ]

0 5 10010 20 30 40 50 60 70 80 90

0

2

4

6

8

10

12

14

15 25 35 45 55 65 75 85 95

0 10010 20 30 40 50 60 70 80 905 15 25 35 45 55 65 75 85 95

0,0

1,0

2,0

3,0

4,0

5,0

6,0

7,0

Rope length from fix point [ % ]

No.

of

cycl

es p

er h

oist

ing

cycl

e [

- ]

Lifting height25/50/75/100%

16

Page 19: Casar Bending Cycle

Analysis of the bending cycle distribution of 1- to 8-part electric hoists

Figure 23: Number of bending cycles depending on the rope length for lifting heights of 25%, 50%, 75% and 100% of the maximum lifting height (7-part hoist)

0 10010 20 30 40 50 60 70 80 905

No.

of

bend

ing

cycl

es [

- ]

Rope length from fix point [ % ]

15 25 35 45 55 65 75 85 95

0

2

4

6

8

10

12

14

Lifting height100%

No.

of

bend

ing

cycl

es [

- ]

0

2

4

6

8

10

12

14

Lifting height25%

No.

of

bend

ing

cycl

es [

- ]

0

2

4

6

8

10

12

14

Lifting height50%

No.

of

bend

ing

cycl

es [

- ]

0

2

4

6

8

10

12

14

Lifting height75%

17

Page 20: Casar Bending Cycle

Analysis of the bending cycle distribution of 1- to 8-part electric hoists

9. The 8-part hoist

Figure 24 shows the maximum number of bending cycles for one full hoisting cycle (=1x lifting, 1x lowering) as a function of the lifting height. Figure 26 (next page) shows the distribution of bending cycles as a function of the rope length (expressed in % of the total rope length) for one full hoisting cycle (=1 x lifting, 1 x lowering) for lifting heights of 25%, 50%, 75% and 100% of the maximum lifting height. Figure 25 shows the average number of bending cycles for a hoist which lifts the block to these four heights with the same frequency.

Figure 24: Maximum number of cycles depending on the lifting height

Figure 25: Distribution of bending cycles per hoisting cycle if lifting heights of 25%, 50%, 75% and 100% of the maximum lifting height occur with the same frequency

Lifting height [ % of the maximum lifting height ]

No.

of

cycl

es p

er h

oist

ing

cycl

e [

- ]

0 5 10010 20 30 40 50 60 70 80 9015 25 35 45 55 65 75 85 95

0

2

4

6

8

10

12

14

16

0 10010 20 30 40 50 60 70 80 905 15 25 35 45 55 65 75 85 95

0,0

1,0

2,0

3,0

4,0

5,0

6,0

7,0

8,0

Rope length from fix point [ % ]

No.

of

cycl

es p

er h

oist

ing

cycl

e [

- ]

Lifting height25/50/75/100%

18

Page 21: Casar Bending Cycle

Analysis of the bending cycle distribution of 1- to 8-part electric hoists

Figure 26: Number of bending cycles depending on the rope length for lifting heights of 25%, 50%, 75% and 100% of the maximum lifting height (8-part hoist)

0 10010 20 30 40 50 60 70 80 905

No.

of

bend

ing

cycl

es [

- ]

Rope length from fix point [ % ]

15 25 35 45 55 65 75 85 95

0

2

4

6

8

10

12

14

16

Lifting height100%

No.

of

bend

ing

cycl

es [

- ]

0

2

4

6

8

10

12

14

16

Lifting height75%

No.

of

bend

ing

cycl

es [

- ]

0

2

4

6

8

10

12

14

16

Lifting height50%

No.

of

bend

ing

cycl

es [

- ]

0

2

4

6

8

10

12

14

16

Lifting height25%

19

Page 22: Casar Bending Cycle

Analysis of the bending cycle distribution of 1- to 8-part electric hoists

1

2

3

4

5

6

7

8

0

1

2

3

4

5

6

7

1

2

2

2

3

4

4

4

1

2

3

4

5

6

7

8

1

3

5

6

7

9

10

11

1

3

5

7

9

11

13

15

Number ofparts [-]

Number ofsheaves [-]

BC for 25%lift. height [-]

BC for 50%lift. height [-]

BC for 75%lift. height [-]

BC for 100%lift. height [-]

Figure 27: Maximum number of bending cycles (BC) depending on the lifting height

10. Summary

During every lifting operation, the most stressed rope section can, at most, pass over every sheave once (= 1 bending cycle each) and spool onto the drum (= 1/2 bending cycle). During every lowering operation it can at maximum spool off the drum (= 1/2 bending cycle) and pass over every sheave once (= 1 bending cycle each). In total, the maximum number of bending cycles which can be generated during a full hoisting cycle (= 1 x lifting, 1 x lower-ing) is therefore equal to twice the number of sheaves plus one.

100% lifting height:Maximum number of bending cycles per lift

= 2 • number of sheaves + 1.

Figure 27 shows the maximum number of bending cycles which the eight hoists generate with lifting heights of 25%, 50%, 75% and 100% of the maximum possible lifting height. As can been seen, the maximum possible number of bending cycles (= 2 • number of sheaves + 1) is generated by every one of the hoists in hoisting cycles lifting to 100% of the maximum possible lifting height. In hoisting cycles lifting to only 50% of the maximum possible lifting height, the maximum number of bending cycles generated corresponds to the number of rope parts.

20

Page 23: Casar Bending Cycle

Analysis of the bending cycle distribution of 1- to 8-part electric hoists

Figure 28: Distribution of bending cycles per hoisting cycle if lifting heights of 25%, 50%, 75% and 100% of the maximum lifting height occur with the same frequency

50% lifting height:Maximum number of bending cycles per lift

= number of rope parts.

Figure 28 shows the average number of bending cycles which are gener-ated when the block is lifted to lifting heights of 25%, 50%, 75% and 100% with the same frequency.

Number ofparts [-]

Number ofsheaves [-]

Number ofbending cycles [-]

Approxi-mation [-]

1

2

3

4

5

6

7

8

0

1

2

3

4

5

6

7

1.00

2.50

3.50

4.25

5.00

6.00

6.75

7.50

2.00

2.80

3.60

4.40

5.20

6.00

6.80

7.60

100

12

2.9

3.5

4.0

0.0

0.7

1.3

Error[%]

The number of bending cycles per hoisting cycle can be approximated by the following equation:

Random lifting height:Maximum number of bending cycles per lift

= 1.2 + 0.8 • number of rope parts.

Figure 28 compares the number of bending cycles calculated by this for-mula with the real number. As can be seen, the approximation is very good for all hoists with sheaves, i.e. for all hoists except the single-part hoist. The formula either predicts the exact fi gure or calculates a slightly higher fi gure. The prediction will, therefore, always be on the conservative side.

21

Page 24: Casar Bending Cycle

Analysis of the bending cycle distribution of 1- to 8-part electric hoists

Figure 29 compares the real number of bending cycles with the number of bending cycles predicted by the formula.

For the analysis presented here, the geometry of the reeving system has deliberately been chosen so that the reeving itself is located close to the drum. With increasing distance from the drum the maximum possible number of bending cycles per hoisting cycle can only decrease. Therefore, the formulas presented here will also be on the conservative side for increasing distances from the drum.

Of course, similar analyzes can also be made for your individual rope drive. The results will be the more accurate, the more details of the mode of operation of the machine are known. Do not hesitate to contact Casar or the author.

1

2

0

3

4

5

6

7

8

1 2 3 4 5 6 7 8

Number of parts [-]

No.

of

bend

ing

cycl

es [

-]

Figure 29: Real number of bending cycles (thick line) and approximation (dotted line)

Dipl.-Ing Roland VerreetWire Rope Technology AachenGrünenthaler Str. 40aD-52072 Aachen

Tel. +49 (0)2 41- 17 31 47Fax +49 (0)2 41- 12 98 2e-mail: [email protected]

© 2004 PR GmbH, Aachen, Germany. Layout and Typesetting: PR GmbH, Aachen, Germany. Cartoon: Rolf Bunse, PR GmbH, Aachen, Germany. Diagrams by the author. Reproduction, in whole or part, only with written permission of the author.

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Page 25: Casar Bending Cycle

Analysis of the bending cycle distribution of 1- to 8-part electric hoists

Two-part OperationNon-rotation-resistant ropes may be used when operating a two-part system with smaller lifting heights. With greater lifting heights, however, rotation-resistant ropes are compulsory. The direction of lay must be chosen contrary to the pitch of the drum. When operating with one left hand grooved drum and one right hand grooved drum, either left hand or right hand lay ropes can be used. As one rope end will always be twisted by one of the drums, a rope with plastic layer between the steel core and the outer strands (Casar Stratoplast or Turbo-plast) must be used when the lifting heights are small. Casar Quadrolift is recommended for greater lifting heights.

2/1

CASAR StarliftCASAR EuroliftCASAR PowerliftCASAR Powerplast

One-part OperationWhen lifting a load with one part, only rotation-resistant ropes must be used. The direction of lay must be chosen contrary to the pitch of the drum.

Both rope ends wind-ing on two left hand or two right hand groov ed drums: cf. 2/1. One rope end winding on a left hand, the other winding on a right hand grooved drum:

Greater lifting heights:CASAR Quadrolift

Small lifting heights:CASAR StratoplastCASAR TurboplastCASAR Superplast

Both rope ends wind-ing on two left hand or two right hand groov ed drums: cf. 2/1. One rope end winding on a left hand, the other winding on a right hand grooved drum:

Greater lifting heights:CASAR Quadrolift

Small lifting heights:CASAR StratoplastCASAR TurboplastCASAR SuperplastCASAR Paraplast

1 drum, 2/2 2 drums, 2/2 2/2 - 2

Greater lifting heights

CASAR StarliftCASAR EuroliftCASAR PowerliftCASAR PowerplastCASAR Quadrolift

Small lifting heights

CASAR StratoplastCASAR TurboplastCASAR AlphaliftCASAR SuperplastCASAR Paraplast

Greater lifting heights

CASAR StarliftCASAR EuroliftCASAR PowerliftCASAR PowerplastCASAR Quadrolift

Small lifting heights

CASAR StratoplastCASAR TurboplastCASAR AlphaliftCASAR SuperplastCASAR Paraplast

11. The right rope for electric hoists

1/1

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Page 26: Casar Bending Cycle

Analysis of the bending cycle distribution of 1- to 8-part electric hoists

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Fax No. +49 (0)6841 / 8091 359

Please send me free of charge the following brochures:

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....... Copies You always get what you pay for

....... Copies Handling, installation and maintenance

....... Copies Technical documentation

....... Copies Wire rope end connections

....... Copies A short history of steel wire ropes

....... Copies Wire rope inspection

....... Copies Calculating the service life of running steel wire ropes

....... Copies The rotation characteristics of steel wire ropes

....... Copies Analysis of the bending cycle distribution on electric hoists

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Page 27: Casar Bending Cycle

Analysis of the bending cycle distribution of 1- to 8-part electric hoists

Page 28: Casar Bending Cycle

Analysis of the bending cycle distribution of 1- to 8-part electric hoists

CASAR DRAHTSEILWERK SAAR GMBHCasarstrasse 1 • D-66459 KirkelPostfach 187 • D-66454 KirkelVerkauf Inland:Tel.: + 49-(0)6841 / 8091-320Fax: + 49-(0)6841 / 8091-329E-mail: [email protected] Export:Tel.: + 49-(0)6841 / 8091-350Fax: + 49-(0)6841 / 8091-359E-mail: [email protected]://www.casar.de 10

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