Roller chains are a transmission option when the torque involved in the design is not supported by a belt transmission, when the system does not allow transmission slippage or when there is a special request, such as transporting materials with the use of additions to chains.
There are currently several types on the market, brands, materials for the varied applications possible with roller chains.
Thus, chains are classified and manufactured according to specific standards. We can say:
ANSI B 29.1 (SO)
ABNT & ISO R-606
DIN8188
FROM 8187 (BS)
FROM 8180
The most well-known and usual standard among chain manufacturers is the ASA Standard.. Thus, it is very common in the specification to describe the current norm and not the pitch.. For example:
ASA25 = Passo 6,35 (1/4")
ASA35 = Step 9,525 (3/8")
ASA40 = Step 12,7 (1/2")
ASA50 = Step 15,875 (5/8")
ASA60 = Step 19,05 (3/4")
ASA80 = Step 25,4 (1")
ASA100 = Step 31,75 (1 1/4")
And so on.
Some observations regarding the gears for chains are of fundamental importance for the correct application and specification in the project.. Here are the ones to watch out for:
01-The ideal for the drive is that the number of teeth of the drive gear is greater than 17 .
02-The ideal for the drive is that the number of teeth of the driven gear is less than 120 .
03-The ideal for the drive is the reduction can be of 1:7, not maximum 1:10.
04-In reductions greater than 1:3 the distance between centers must not be less than the difference between the diameter of the driven gear and the diameter of the driving gear, to ensure a minimum arc of contact of 120°, in the drive gear.
05-The number of teeth of the driven and driven gear should be chosen from one of the gears normally found in the market.. First select the default gear, then calculate the other by the following formula:
number of teeth eng. engine = (RPM eng. moved x number of teeth Eng. Moved) / RPM eng. engine
or
number of teeth eng. moved = (RPM eng. motor x number of teeth Eng. Engine) / RPM eng. moved
06-The selected Drive must be analyzed to make sure that the physical space supports the transmission.
07-The distance between gear centers must not exceed 80 times the current pitch.
08-The distance between centers must be equal to or greater than the minimum distances recommended according to the table below:
Step 9,525mm - Between Min Centers:152mm
Step 12,7mm - Between Min Centers:228mm
Step 15,875mm - Between Min Centers:305mm
Step 19,05mm - Between Min Centers:380mm
Step 25,4mm - Between Min Centers:530mm
Step 31,75mm - Between Min Centers:686mm
Step 38,1mm - Between Min Centers:838mm
Step 44,45mm - Between Min Centers:990mm
Step 50,8mm - Between Min Centers:1143mm
Step 63,5mm - Between Min Centers:1450mm
Step 76,2mm - Between Min Centers:1676mm
09-The final design must have adequate capacity taking into account the power limits for the different current steps.. (See downloadable material).
10-For gears less than 24 teeth, speeds above 600RPM, reductions above 1:4 or heavy loads, specify gears with hardened teeth.
See below, available for consultation, technical content for calculation, selection and sizing of roller chains:
That's it for today Folks! Good Study and Good Projects!