When you select chain and design conveying system please describe your purpose of the usage as in detail as possible for the most appropriate recommendation by DBC. Proper chain selection eliminates causes of problems in advance after installing/operating the system, and saving much of maintenance costs as well.
Take advantage of DBC's over 40 year-old accumulated experience and know- how.
1. Component Part of Roller Chain
A roller chain is completed by series of assembly of a Roller Link(=Inner Link) composed of two pieces of plates, bushings and rollers & a Pin Link(=Outer Link) composed of two plates and a pin.
2. Dimensions and Abbreviation of Main Parts
1) Chain is generally identified by 3 distinctive features below
2) Link Countering
-Number of links of the chain is understood same as that of pitch.
3. Connection of Roller Chains
A chain is assembled by pin links and roller links in turn, and finally done by connecting links free from connection and disconnection. Those of representative 3 kinds are;
4. Procedure of Chain Selection
[Table1] DBC Roller Chain Tentative Selection Table
5. Chain Selection
5-1. General way to select chain
1) Conditions to be considered:
- Shock Loads
- Source of power
- Feature of driven equipment
- Drive sprocket rpm and shaft diameter
- Driven sprocket rpm and shaft diameter
- Center distance between sprockets
- Environments and usage
- Method of lubrication
2) Multiple strand factor (K1)
Defining corrective loads decided by drive tools and form of the load
[Table 2] Multiple strand factors (K1)
No. of Chain strand
1
2
3
4
5
6
Service factor
1
1.7
2.5
3.3
4.1
4.9
3) Decision of designing power
Transmittable power corrected by number-of-strand-depended 'multiple strand factor'.
a. Single strand chain: designing power = transmittable power x multiple strand factor (K1)
b. Multi strand chain: designing power = [transmittable power x K1] / no. of strand
4) Decision of roller chain and number of teeth of sprocket
The graph [Table1] shows number of rotation of shaft, designing power, proper selection of roller chain & sprocket (teeth number) and their power transmission ability. In addition, decision on number of teeth of the sprocket should be considered together with correlation of driving shaft and its hub.
5) Selecting for number of teeth for large sprocket
The selection should be made based on driving ratio increased by the small sprocket's teeth number.
6) Selection example
* An appropriate roller chain and a sprocket for 3.5kw center compression pump that rotates at 1,800rpm:
a. Usable modulus in Table 4 : 1.3
transmittable power X usable modulus = designing power
→ 3.5kw X 1.3 = 4.6kwW
b. You will find that it is DBC40 chain and sprocket with 13-20 teeth by searching for cross point of 1,800rpm and 4.6kw in the graph.
c. Be referred to Table of Power Transmission Ability which indicates that power transmission ability 5kw is safe at speed of 1,800rpm for DBC40 and sprocket with 14 teeth(the table is presented in DBC electronic catalogue).
d. In conclusion successful selection to be DBC40 & small sprocket with 14 teeth.
5-2. Selecting chain for special environment
Selective conditions for low-speed operation should be based when speed of the chain is slower than 50m/min., considering of importance of fatigue strength more than abrasive elongation.
1) At low speeds operlation
Selective conditions and process for chain that repeats stops and runnings frequently, or that operates slower than 50m/min. are as follow;

a. Find out the maximum power and rpm of the smallest chain/sprocket on the graph.
b. Indicate maximum load on the chain
c. Fix Service Factor out of Table 4.
d. Fix Speed Factor out of Table 3.
e. Substitute figures into above formula for ensuring of safety to allowable load

Note : Additional correction on usable modulus is needed in environment of frequent stops and runnings or in direction-changeable operation.

2) Operation in special conditions
Choosing stainless steel chain or anti-corrosion/anti-heat typed chain is recommended in some working environment where severe heat or corrosion is expected.
[Table 3] Speed Factor
Chain Speed(m/min)
Speed Factor
under 10
1.0
10 - 20
1.1
20 - 30
1.2
30 - 40
1.3
40 - 50
1.4
50 - 70
1.6
6. Kilowatt Rating Tables
This table is set up based on the following conditions;
a. Under normal working environment
b. For single stranded chain only
c. Service Factor: 1.0
d. With proper lubrication
e. Driving/driven shaft installed horizontally
f. Minimum changes in load
Loaded weight may be different according to types of driving power and driving tool so appropriate adopt of usable modulus is required. Apply corrective modulus in Table 2 for multi-stranded chain.
[Table 4] Service Factor
Load Types?/div>
Driven Equipment
Source of Power
Motor/Turbine
Inner burningby hydraulicpressure power transmission
Inner burningby machinerypower transmission
uniform load
Agitators, generators, centrifugal pumps, ordinary machines with small load fluctuation and non-reversing
1.0
1.0
1.2
slightly irregular load
automatic furnaces, dryers, general machine tools, compressors, general work machines, general paper mills and Conveyor & elevator with mild shock load
1.3
1.2
1.4
irregular load
Press, construction or mining machines, vibration machines and machinery with severe load or reversing
1.5
1.4
1.7
-Note
a. Proper lubrication and normal temperature -10˚C∼60˚C in working environment is required.
b. Apply Service Factor of over 2.0 and use lubricant available for low temperature in case it is under -40˚C in the working environment.
6-1. Chain pitch
We would recommend that you should use small-pitched chain, and multi-stranded chain is advised to consider when load on the single-stranded chain is out of its maximum allowable load. In case the distance between pivots is too short due to limited space of the equipment, or diameter of the sprocket is small, considering of multi-stranded chain and sprocket with many teeth is required.
6-2. Number of teeth for small sprocket
You need to choose a sprocket with more than 17 teeth for low impact and low noise, but one with 11 teeth for low speed operation and one with more than 25 teeth for high speed operation is recommended.
6-3. Heat treatment on teeth
Heat treated sprocket on its teeth will be essential for following cases;
a. low speed with heavy load drive
b. high speed drive
c. large ratio drives
d. abrasion and corrosion environment
6-4. number of teeth for large sprocket
Worn chain makes its pitch elongated, and interrupt normal operation of the sprocket and chain in the end. As shown on the graph below, chain life is determined by abrasion rate per number of teeth of the large sprocket. In general abrasion life of roller chain is understood same as that of allowable abrasion limit, whose rate is 1.5% to 2.0%.
6-5. Minimum contact angle and driving ratio
For smoother and safe drive, contact angle of small sprocket should maintain over 120˙ and driving speed reducing ratio should not be exceeded 1:7 for single-stranded driving operation.
6-6. Variation of Chain Speed
Engagement of roller chain and sprocket is multi-angled type and this causes changes of speed. In addition the more number of teeth the sprocket has, the less change in speed it gets, and vice-versa. As shown on a graph below, change of speed is minimized, i.e. stable, when the number of teeth is over 25.
6-7. Service Factor
[Table 4] is applicable for general power transmission but you are advised to apply extra 'service factor' in below mentioned cases;
- Frequent starts & stops
- Insufficient lubrication
- In vertical drive operation (in which driving pivot is located in lower part)
- Over 2 driving sprockets
- Reverse rotation(drive)
- Loads are changed regulary
6-8. Length of Chain
The required length of chain is computed using the following formula.
L = (N+n)/2 + 2C + [(N-n)/6.28]2/C
N : Number of teeth in large sprocket
n : Number of teeth in small sprocket
C : Shaft center pitch
L : Chain length
6-9. Shaft Center Distance
The shaft center distance C is calculated using the following formula.
C = 1/8[2L - L - n + √[(2L-N-n)2-0.811(N-n)2]
6-10. Chain speed and Calculation of load on chain
a. Chain speed
V = P x N x n/1000 (m/min)
V : chain speed (m/min)
P : chain pitch (mm)
N : number of teeth in sprocket
n : rpm of sprocket
b. Load on chain
P = 102kw/V (kg)
P : load on chain (kg)
V : chain speed (m/min)
6-11. Installation and Arrangement of Chain
When designing the wrapping transmission drive, the center line of both sprockets should be close to horizontal. The vertical drive arrangement is not recommended because the chain is apt to be derailed from the sprocket even in case of minimal elongation. Also the angle of inclination should be up to 60°, if it is possible. And a minimum center distance should be sufficient to give clearance between the teeth of the two sprockets. In general, the center distance of the sprockets should be 30 to 50 times chain pitch. But the center distance of the sprockets should be less than 20 times the chain pitch, when the chain is subjected to fluctuating load,
6-12. Prevention of Chain Vibration
If a vibration takes place due to transmission condition, in this case, you should install 'Guide Stopper' to prevent vibration.
6-13. The amount of Chain Sag
The slack should be on the lower side.
In general the amount of chain sag (S-S') is generally 4% of the span but the sag should be 2% of the span for the following applications:
- Heavy load and frequent starts
-The center line of sprockets is vertical or almost vertical
-Shaft center distance is more than one meter
-Travel direction of chain is often reversed
6-14. Aligning Shafts and sprockets
The two shafts should be same and two shafts be aligned horizontally after install sprocket and then apply a straight edge to the sprocket surfaces to see if two sprockets are in the same plane.
7. Lubrication
7-1.Application of lubricant to chains
A Roller Chain consists of a series of connected components that must be properly lubricated to obtain the maximum service life.
For example the elongation of roller chain is the result of wear caused by friction between the pins and bushings.
If you lubricate as below picture, chain life-time extends remarkably because an oil film will prevent direct contact between chain components. Also, lubricant give cooling effect , decreasing noise and buffer action of absorbing impact at high speed driving speed.
7-2. Selection of the lubricant
The lubricants suggested for specific temperature ranges are shown in the following selection table. (The heavy oil or Grease not suitable for Roller Chain of lubricant.)
Temp( ˚c ) Viscosity
-10℃ ∼ 0℃
SAE 20
0℃ ∼ 40℃
SAE 30
40℃ ∼ 50℃
SAE 40
50℃ ∼ 60℃
SAE 50
7-3. Type of Lubrication
There are three basic methods of lubrication for roller chain drives. Close adherence to these recommended types of lubrication is essential in obtaining the maximum service life of a chain drive. These recommended types of lubrication, as shown in the , are determined by the chain speed and the amount of power transmitted.
Type of
Lubrication
Lubricating Method Lubrication amount
& Method
Attention
A I Manual Lubrication :
Oil is applied with a oil filler or oil brush on the slack side of the chain
- It should be applied about every 8 hours or as often as necessary to prevent the bearings from becoming dry.
- Do not attempt to manually lubricate of service any chain while it is operating. Serious injury could result.
- Acceptable for slow speed : generally not over 200m/ min
II Drip Lubrication :
The oil is supplied by drip feed by using oil casing
- About 5 to 20 drops of oil per min. or as enough as necessary to prevent the chains from over heating
- According to change of the speed, should increase amount.
- Acceptable for slow speed : generally not over 200m/min
B I Oil Bath Lubrication :
The Chain is installed in a leakless casing.
- The oil depth 'H' should be 6 to 12mm deep.
- The oil level should be such that the pitch line of the chain is just submerged.
- This method is suitable for chains operating at up to approximately 450m/min
- To prevent excessive heat generation, only a short section of chain should run through the bath.
II Lubrication by Slinger Disc :
The Chain is installed in a leakless casing and oil is splashed on the chain.
-The oil depth 'H' should be 12 to 25mm deep.
- If the width of the chain is larger than 125mm, attach slinger discs to both side.
- The circumferential speed should be at least 200m/min.
- The chain should not pass through oil
C Forced Feed Lubrication :
Lubricant is pumped onto the chain under pressure.
- This is the preferred method of lubrication, particularly for drives with heavy loads or high speeds.
- Use for speeds higher than Type B limit and for chains operating at up to approximately 760m/ min.
- The oil should be directed to the inside of the slack strand with one oil stream for each 1 inch of chain width.
Chain Speed
( m/min )
Chain Nr.
DBC 60 and under DBC 80 & 100 DBC 120 & 140 DBC 160 & over
500~800 1.0ℓ /min 1.5ℓ /min 2.0ℓ /min 2.5ℓ /min
800~1,100 2.0ℓ /min 2.5ℓ /min 3.0ℓ /min 3.5ℓ /min
1,100~1,400 3.0ℓ /min 3.5ℓ /min 4.0ℓ /min 4.5ℓ /min
Chain drives should be inspected regularly to assure that the lubrication is functioning properly. For example, pin of chain or bushing is discolored (redidish-brown color appearing) or wear happens appears, it means that the chain will not be sufficiently lubricated.
And regardless of the lubricating system used, the roller chain must be washed periodically with petroleum or gasoline.
8. Attachments of roller chain
Various attachment that attach to roller chain is parting as following.
8.1 Standard attachment
Terminology of Standard Attachment
Type of Attachment Name ofAttachment Description
General-type
A
Bend Att.* , One Side, Horizontal type Att.
A-1
Bend Att. , One Side, Horizontal type Att. One Hole
K
Bend Att., Both Side, Horizontal type Att.
K-1
Bend Att., Both Side, Horizontal type Att. One Hole
SA
Bend Att. , One Side, Vertical type Att.
SA-1
Bend Att. , One Side, Vertical type Att. One Hole
SK
Bend Att., Both Side, Vertical type Att.
SK-2
Bend Att., Both Side, Vertical type Att., Two Hole
WIDE TYPE
W
Wide Contour,Type Attachment
WA
Wide Contour, One Side, Horizontal type Att
WSA
Wide Contour, One Side, Vertical type Att.
WK
Wide Contour, Both Side
WSK
Wide Contour, Both Side, Vertical type Att.
WA-1
Wide Contour, One Side, Horizontal type Att., One Hole
Extended Pin Type
D-1
One Pin in Link extended
D-3
Both Pins in Link extended
Note) Att* = Attachment

* Example of type indication : DBC 80 SA-2/ 2L x 120L