|
Ref No. |
Material |
Internal Link Length (mm) |
External Link Width (mm) |
Link Wire Diameter (mm) |
Links Per Foot (LPF) |
|
|
|
|
|
|
|
|
1 |
Brass |
4.80 |
3.60 |
0.90 |
63.1 |
|
2 |
Brass |
5.02 |
6.50 |
0.86 |
58.8 |
|
3 |
Brass |
5.70 |
4.20 |
1.00 |
53.1 |
|
4 |
Iron |
6.00 |
4.40 |
1.00 |
50.5 |
|
5 |
Brass |
6.00 |
4.40 |
1.00 |
50.5 |
|
6 |
Iron |
6.10 |
4.80 |
1.00 |
49.6 |
|
7 |
Brass |
6.10 |
4.80 |
1.00 |
49.6 |
|
8 |
Brass |
6.30 |
5.30 |
1.30 |
47.9 |
|
9 |
Brass |
6.30 |
4.60 |
1.05 |
48.0 |
|
10 |
Brass |
6.40 |
4.60 |
1.05 |
47.2 |
|
11 |
Iron |
6.50 |
5.00 |
1.50 |
46.4 |
|
12 |
Brass |
6.50 |
5.95 |
1.62 |
46.6 |
|
13 |
Brass |
6.56 |
5.35 |
1.35 |
46.4 |
|
14 |
Iron |
6.60 |
3.60 |
0.90 |
46.0 |
|
15 |
Brass |
6.60 |
5.00 |
1.35 |
45.8 |
|
16 |
Iron |
6.60 |
5.00 |
1.35 |
45.8 |
|
17 |
Iron |
6.80 |
3.70 |
0.90 |
44.6 |
|
18 |
Brass |
6.80 |
3.70 |
0.90 |
44.6 |
|
19 |
Iron |
7.20 |
6.70 |
1.60 |
41.8 |
|
20 |
Iron |
7.20 |
4.80 |
1.18 |
40.0 |
|
21 |
Brass |
7.20 |
4.80 |
1.18 |
40.0 |
|
22 |
Iron |
7.25 |
5.00 |
1.20 |
41.7 |
|
23 |
Brass |
7.25 |
5.00 |
1.20 |
41.7 |
|
24 |
Iron |
7.90 |
5.10 |
1.55 |
38.0 |
|
25 |
Brass |
7.90 |
5.10 |
1.55 |
38.0 |
|
26 |
Iron |
8.10 |
4.60 |
1.00 |
37.4 |
|
27 |
Brass |
8.10 |
4.60 |
1.00 |
37.4 |
|
28 |
Iron |
8.30 |
6.90 |
1.80 |
36.0 |
|
29 |
Brass |
8.30 |
6.60 |
1.80 |
36.8 |
|
30 |
Iron |
8.50 |
7.00 |
1.80 |
36.0 |
|
31 |
Iron |
9.00 |
6.70 |
1.90 |
33.4 |
|
32 |
Iron |
9.45 |
5.14 |
1.18 |
31.0 |
|
33 |
Chromed Brass |
9.60 |
6.60 |
1.50 |
31.5 |
|
34 |
Brass |
9.60 |
6.60 |
1.50 |
31.5 |
|
Sprocket Wheel |
Sprocket Wheel |
Sprocket Wheel |
Sprocket Wheel |
Internal Link |
Closest |
|
No. of Teeth |
Effective Diameter |
Circumference |
Tip to Tip Distance |
Length Required |
Chain Match |
|
|
(mm) |
(mm) |
(mm) |
(mm) |
LPF |
|
6 |
20 |
62.84 |
10.47 |
5.76 |
53.1 |
|
6 |
22 |
69.12 |
11.52 |
6.34 |
47.9 |
|
6 |
24 |
75.41 |
12.57 |
6.91 |
44.6 |
|
6 |
26 |
81.69 |
13.62 |
7.49 |
38.0 |
|
6 |
28 |
87.98 |
14.66 |
8.06 |
37.4 |
|
6 |
30 |
94.26 |
15.71 |
8.64 |
33.4 |
|
6 |
32 |
100.54 |
16.76 |
9.22 |
31.0 |
|
8 |
22 |
69.12 |
8.64 |
4.75 |
63.1 |
|
8 |
24 |
75.41 |
9.43 |
5.18 |
53.1 |
|
8 |
26 |
81.69 |
10.21 |
5.62 |
53.1 |
|
8 |
28 |
87.98 |
11.00 |
6.05 |
49.6 |
|
8 |
30 |
94.26 |
11.78 |
6.48 |
46.4 |
|
8 |
32 |
100.54 |
12.57 |
6.91 |
44.6 |
|
8 |
34 |
106.83 |
13.35 |
7.34 |
41.7 |
|
8 |
36 |
113.11 |
14.14 |
7.78 |
38.0 |
|
8 |
38 |
119.40 |
14.92 |
8.21 |
36.0 |
|
8 |
40 |
125.68 |
15.71 |
8.64 |
36.0 |
|
8 |
42 |
131.96 |
16.50 |
9.07 |
33.4 |
|
8 |
44 |
138.25 |
17.28 |
9.50 |
31.5 |
|
10 |
28 |
87.98 |
8.80 |
4.84 |
63.1 |
|
10 |
30 |
94.26 |
9.43 |
5.18 |
58.8 |
|
10 |
32 |
100.54 |
10.05 |
5.53 |
53.1 |
|
10 |
34 |
106.83 |
10.68 |
5.88 |
50.5 |
|
10 |
36 |
113.11 |
11.31 |
6.22 |
47.9 |
|
10 |
38 |
119.40 |
11.94 |
6.57 |
46.4 |
|
10 |
40 |
125.68 |
12.57 |
6.91 |
44.6 |
|
10 |
42 |
131.96 |
13.20 |
7.26 |
41.7 |
|
10 |
44 |
138.25 |
13.82 |
7.60 |
38.0 |
|
10 |
46 |
144.53 |
14.45 |
7.95 |
38.0 |
|
10 |
48 |
150.82 |
15.08 |
8.29 |
36.8 |
|
10 |
50 |
157.10 |
15.71 |
8.64 |
36.0 |
Clock Chains Explained
CLOCK CHAINS
Actions to find correct chain replacement.
Note: Clock chain is one of the most difficult items to select and purchase online. Frequently the sprockets are worn, or the wrong chain has been fitted. However, with care and attention the correct replacement can be found and fitted.
Determining the correct type of chain:
- If you have a chain that is correct and can be measured then just determine the links per foot required and select the required chain from the table.
- If you have a cuckoo clock that does not have any chains or has chains that do not work correctly there is a way to determine what chain to use.
- Measure the effective diameter of the pulley excluding the sprockets, in millimetres. If the sprockets are wider at the base, as in the example, the effective diameter is the lowest point on the sprockets reached by the horizontal chain links. This should be self evident by wear marks on the chain/sprockets.
- Keep in mind that most cuckoo clocks sprockets / chains use every other link , so the distance between sprocket teeth must match the distance between 3 centres of links.
- Use the formula to find the circumference of a circle (Pi x Dia); to find the distance around the sprocket exterior; then divide that by the number of teeth to determine the required distance between every other link ie: the distance between sprocket tooth ends.
- The wire diameter must be such that the links will sit in the saddle of the sprocket enclosure without climbing out as the sprocket turns as the clock is running or when the clock is being wound. The links should sit approximately 50% of the way down on the tooth.
- The final test, however, is whether or not the chain pulls through without any places that bind up. The chain must run though SMOOTHLY or the clock will not work. If the links climb up on the sprocket teeth when the chain is pulled though, then the chain is not the correct link per foot count or the wire diameter is wrong.
- We have tabulated a wide range of results to make life easy for you. There are a couple of points that also need to be stressed.
- Due to the angular displacement of the sprocket teeth (angle of attack) a percentage tolerance is added to the calculated result to allow a ‘clearance fit’ to be obtained. This allows the link to ‘drop’ onto the sprocket tooth and not bind or ride up.
- We have included this ‘fudge factor’ as some might call it into our tabulated results. This will hopefully ensure a successful result and a get it right first time approach.
Clock Chains
- The list below is in ascending Internal Link Length order.
- External link length is the Internal link length plus two wire diameters.
- Links per foot is 304.8mm (-
2 wire diameters). (304.8mm is 12 inches = 1 foot (imperial) - Internal length is 304.8mm -
(2 wire diameters) divided by the links per foot. - *All chains are supplied in 6 foot lengths.*
Chains are supplied in whatever material is available to the manufacturer. Iron is either steel or nickel plated steel. Brass means either solid brass or brass plated steel. The prices vary accordingly.
Angular displacement of 8 sprocket wheel tooth tips is 45 degrees
Effective Sprocket Wheel Diameter
Sprocket Wheel Teeth Tips Distance is actually 2 Internal Link Lengths on chosen chain
Distance is Pi Multiplied by Effective Diameter then Divided by Number of Sprocket Teeth
Pi = 3.142 approx.
Overall Length of Link
Link Wire Diameter