SIT Automatic Tensioners TA Series
Spring-loaded automatic tensioners for belts and chains: TA base unit with sprocket (RDF, RDR), low-friction head (PA) or idler (RU).
SIT Automatic Tensioners - TA Series
SIT TA automatic tensioners are universal spring-loaded tensioners that keep a constant tension on belts and chains and automatically take up belt and chain elongation. According to the manufacturer, constant tension increases drive life by up to 40% and reduces vibration and noise by 15%.
Design and features
- Body (bases TA-1 and TA-2) in high-strength light alloy, lever in galvanised steel.
- Pre-loaded elastic elements in special high-yield steel inside the body give an extremely constant working load.
- A sprocket, a low-friction head or an idler can be mounted on the lever; double and triple sprockets or heads tension duplex and triplex chains.
- Fixing with a screw from the inside or from the outside.
- Working angle greater than 45° in both directions of rotation; maximum working temperature 100°C (higher values on request).
- Watertight: resistant to chemical and abrasive agents, suitable for harsh environments.
- Also usable wherever pressure, tension or shock absorption must be applied.
TA base unit
TA1 (smaller) and TA2 bodies are combined with different galvanised-steel levers: levers 110, 111, 115, 118 on TA1 and 210, 218, 227 on TA2. Ordering example: TA1 110 (base type + lever type).
| Model | Force min. (N) | Force max. (N) |
|---|---|---|
| TA1-110 / 111 / 115 / 118 | 100 | 210 |
| TA2-210 / 218 / 227 | 200 | 350 |
Versions
| Series | Lever fitting | Use |
|---|---|---|
| TA-RDF | Fixed sprocket on a watertight ball bearing | Roller chains; double and triple chains with the matching sprockets |
| TA-RDR | Axially adjustable sprocket on a watertight ball bearing | Roller chains - sprocket aligned to the chain without shims |
| TA-PA | Low-friction head in high-density polyethylene | Chains at moderate linear speed, working temperature up to 60°C |
| TA-RU | Galvanised-steel idler on ball bearings (aluminium or nylon on request) | V-belts, synchronous (timing) belts and flat belts |
TA-RDF / TA-RDR chain tensioners - sprocket range
| Base | Chain pitch | Sprocket teeth Z (RDF) |
|---|---|---|
| TA1 | 3/8" x 7/32" | 21 |
| TA1 | 1/2" x 5/16" | 16 |
| TA1 / TA2 | 5/8" x 3/8" | 15 |
| TA2 | 3/4" x 7/16" | 15 |
| TA2 | 1" x 17 mm | 12 |
Ordering examples: TA1 115 RDF 3/8", TA1 110 RDR 3/8", TA1 110 PA 3/8", TA1 110 RU. Special RDS sprockets with a different number of teeth on request.
Mounting instructions
- Always mount the tensioner on the slack side of the belt or chain and, where possible, on the outside of it. The mounting position does not affect tensioner performance.
- For alternating or reversing drives, mount two tensioners, one on each side; the working load is then higher and must be considered at the design stage.
- Install the tensioner perfectly aligned and in the direction of drive.
- On drives with a very long centre distance, use several tensioners to increase the tensioning capacity.
Full dimension tables on request. Source: SIT S.p.A. catalogue "Tenditori automatici SIT - Serie TA / SIT Automatic tighteners - TA Series", 043.01. Brand names are used for identification and technical reference.
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