2.1.2 Double Pitch Roller Chain
Light conveyance: General uses
This is the most commonly used conveyor chain and is utilized widely in the auto parts, electric, electronic, and precision machinery industries (Figure 2.4).
Figure 2.4 Double Pitch Roller Chain
Construction and Features
Double Pitch Roller Chain has the same basic construction as Standard Roller Chain, but double pitch means the chain pitch is twice as long, has flat-shaped link plates, and longer attachments. This series is regulated by ANSI B29.4, ISO 1275-A, and JIS B 1803. Table 2.2 shows the size, pitch, and maximum allowable tension for standard specification Double Pitch Roller Chain.
Among these, four sizes-Numbers 2040, 2050, 2060, and 2080-are most commonly used. The features are shown below:
- Double Pitch Roller Chains have the smallest tolerances for overall length compared to all other types of conveyor chains.
Without attachments: 0 to +0.15 percent of the nominal chain length.
With attachments: 0 to +0.25 percent of the nominal chain length.
|Chain No.||Pitch (mm)||Maximum Allowable
- There are two types of rollers, R-roller (oversized) and S-roller (standard). The S-rollers are used in short-length and slow-speed conveyance. The R-rollers are most commonly used, especially for longer conveyors.
- There are many standard attachments and special attachments (Plus α Alpha series) available for this series.
- Chains sized 2060 and larger have greater rigidity than Standard RS Attachment Chains because the link plates are one size thicker (heavy).
- Due to its light weight, the chain's inertia is smaller.
- Slip-fit, spring-clip-type connecting links are provided for Numbers 2040, 2050, and 2060. Number 2080 has cottered connecting links.
Special sprockets are required for these chains. For the S-rollers, standard sprockets exceeding 30 teeth are used (30-tooth sprocket has 15 effective teeth). The chain engages every second tooth.
Selection and Handling
- Double Pitch Roller Chains are selected according to the allowable roller load and maximum allowable tension.
- When the attachments receive a large bending or twisting force, make sure the chain has adequate strength. In these cases, a larger-pitch roller chain is frequently used because it has a thicker plate and longer attachment.
- In these chains, clearance between the components is small. Chain articulation is easily affected by dirt or contamination in the joints.
- Lubrication-free: LAMBDA® series (operating temperature of −10° to 150°C). O-ring chains are also lubrication-free chains, however, they have bending resistance and sometimes, after engaging the sprockets, the chains retain the articulated position. This may occur at the return side of the chain loop. Therefore, O-ring chains are not suitable for conveyance.
- Environmentally resistant: Special coatings or base materials may be used to add extra resistance.
- Coating: Nickel plating, WP® specification.
- Material: 304 stainless steel SS-type and AS-type with pins, bushings, and small rollers are made of precipitation-hardened stainless steel.