NICE / APOLLO 40BB17H, SPROCKET, SLIDE GATE IDLER
The Nice Apollo 40BB17H idler sprocket is a mechanical chain-drive component used on select Apollo slide gate operators to support smooth chain travel and chain alignment. Unlike a drive sprocket, the idler sprocket does not transfer motor torque directly; it helps guide the chain and maintain the correct path through the slide gate drive assembly. A failing idler can create chain noise, uneven movement, premature chain wear, and side loading on other parts. This part is commonly referenced for Apollo 7251 and 7351 slide gate operators using #40 roller chain. Correct chain pitch, bearing size, mounting position, and chain alignment must be verified so the new sprocket does not wear out quickly.
Compatible With
Commonly associated with the following applications when confirmed by the Apollo/Nice parts diagram and the installed operator configuration:
- Apollo 7251 slide gate operator
- Apollo 7351 slide gate operator
- Select Apollo/Nice #40 chain slide gate assemblies
- Related 7200/7300 style slide gate references when the parts diagram calls for 40BB17H
- Applications requiring the 17-tooth #40 chain idler sprocket with ball bearing
Features and Specifications
| Manufacturer | Nice Apollo |
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| Product Type | Slide gate idler sprocket |
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| Part Number | 40BB17H |
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| Application | Chain idler / slack take-up sprocket |
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| Chain Size | #40 roller chain |
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| Tooth Count | 17 teeth |
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| Bearing | Built-in ball bearing style commonly referenced |
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| Notes | Common references include OD 2.970 in, bore 0.638 in, #40 chain pitch 0.500 in |
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Also Known As / Related Part Numbers
- 40BB17H
- Apollo 40BB17H
- Nice Apollo 40BB17H
- NICE-40BB17H
- Sprocket, slide gate idler
- 17-tooth #40 idler sprocket
- Related but different: 40BS13 drive sprocket
- Related but different: 35B25 quick release sprocket
Technician Note
A seized or loose idler sprocket can damage the chain and drive sprocket. Inspect the entire chain path before installing the replacement.
Before Ordering
- Confirm the operator is a compatible Apollo slide gate model
- Match #40 chain size and 17-tooth idler style
- Inspect chain wear and drive sprocket teeth
- Check bearing play and mounting hardware
- Verify chain alignment after replacement
Professional Advisory
Disconnect power and secure the gate before servicing mechanical or electrical gate operator parts. Use a qualified gate technician for unsafe conditions or line-voltage work.
Product Questions and Answers
Which operators use the 40BB17H idler sprocket?
The 40BB17H idler sprocket is commonly listed for Apollo 7251 and 7351 slide gate operators and related #40 chain slide gate assemblies.
What chain size does 40BB17H work with?
It is designed for #40 roller chain, which has a 1/2 inch pitch.
Is 40BB17H a drive sprocket?
No. It is an idler sprocket used for chain guidance and slack take-up. The 40BS13 is the related #40 drive sprocket reference for 7251/7351.
When does an idler sprocket need replacement?
Replace it when the bearing is rough, the sprocket wobbles, teeth are hooked or worn, or chain movement is noisy even after proper adjustment.
Can I replace only the idler sprocket?
Yes, if the chain, drive sprocket, shaft, and mounting hardware are still in good condition. Worn drive parts should be inspected together.
