What Is the Stihl MS 311 Chain Brake (Safety Test)
The STIHL MS 311 chain brake is a safety device that helps stop the chain when the brake is correctly activated. A proper safety check confirms that the brake can stop a moving chain and that the chain stays still at idle with the brake released. Follow the manual for your saw’s version; never test a suspected fault by cutting.
A chain-brake check is a simple way to spot a serious problem before work begins. It does not prove that every part of the saw is safe, and it cannot replace training, protective gear, or careful handling. Routine checks and cleaning are low-maintenance steps, but a brake that acts slowly or feels damaged needs professional attention.
In training, I explain the test as two separate checks: first, look for chain movement at idle; then, check brake action only by the method in the MS 311 manual. Keeping those checks distinct helps avoid mistaking an engine or chain problem for a brake problem.
What the MS 311 chain brake does
The chain brake is a safety mechanism that is designed to stop the chain when activated. On the MS 311, the front hand guard is linked to the brake. Pushing the guard forward by hand, or certain sudden saw movements, can engage it. The brake does not prevent all kickback injuries.
When engaged, the brake applies force to the chain’s drive system so the chain stops moving around the guide bar. A functioning brake can reduce the danger if the chain is still moving during a kickback, but it cannot make risky cutting safe. Keep both hands on the saw and avoid the guide-bar nose, where kickback can occur.
Pulling the hand guard back toward the front handle releases the brake. The chain should then be able to move when the engine is running and the throttle is applied. Never run the saw with the brake removed, bypassed, slipping, or unverified.
The MS 311 has a 59.0 cm³ engine and a rated power of 3.1 kW. It is intended for ground-based work such as bucking and suitable felling, not for climbing. Its size and power make a sound brake and safe work habits especially important.
What the safety test must confirm
The safety test checks two basic conditions: the chain stays still at idle when the brake is released, and the brake stops chain motion when activated using the procedure in the correct MS 311 manual. Both matter. A good result in one check does not excuse a failure in the other.
A stationary chain at idle helps show that the engine is not driving the chain when you are not pressing the throttle. If the chain creeps, stop using the saw. Do not raise or lower the idle setting to hide the symptom. A service provider should identify the cause.
For the brake check, use the manual’s instructions for your exact model and serial version. Do not make up a test, and do not try to prove the brake works by cutting wood. In particular, never improvise a full-throttle test. If the prescribed check is unclear, ask a STIHL dealer to show you the safe method.
| Check | What you should observe | If it fails |
|---|---|---|
| Idle, brake released | Chain remains still | Stop the engine and have the cause checked |
| Brake activated during the manual’s test | Chain stops promptly | Stop using the saw and arrange service |
| Hand guard and brake parts | No visible damage or obstruction | Do not operate until inspected |
A brake that stops the chain once may still need attention if it feels damaged, acts inconsistently, or is contaminated. Treat uncertainty as a reason to stop, not as a reason to try another test.
Equipment setup and safety preparation
Good preparation lowers the risk of injury during both the test and later cutting. Before starting, wear the protective equipment required by the manual, check the work area, and inspect the saw. A chain-brake test is only one part of this preparation, not a general approval to use the saw.
Wear a helmet with face and eye protection, hearing protection, chainsaw-protective legwear, gloves, and suitable boots. Check your footing, the workpiece, overhead hazards, and your escape path. Keep other people outside the work zone. Do not start or test the saw near anyone who could be struck by the bar or chain.
With the engine off, inspect the hand guard, chain catcher, throttle lockout, bar, chain, and fuel and oil caps. Look for damage, loose parts, or debris around the brake area. Check chain tension as the manual directs. The chain must be the correct type for the bar and saw.
MS 311 bar lengths are listed in a 40–63 cm (16–25 in) range, but approved options vary by market and setup. Common configurations use a 3/8-inch pitch and a .063-inch (1.6 mm) gauge chain. Check the markings on your bar and chain, plus the required drive-link count. Do not assume parts fit because they look similar.
Use fresh unleaded gasoline mixed 50:1 with STIHL two-stroke oil, following the manual’s fuel guidance. Use purpose-made chain and bar oil. Oil flow varies with the saw, bar, oil, and conditions, so there is no single flow-rate check that applies to every setup.
How to perform the chain-brake safety check
The safest approach is to follow the MS 311 manual step by step. Start with the chain stationary and the work area clear. Use only the manual’s stated method for checking brake action. If you cannot confirm that method for your saw, stop and ask a qualified STIHL service provider.
- Prepare the saw. Put on the required protective gear and inspect the saw. Confirm the correct bar and chain are fitted and that the chain is properly tensioned.
- Start as directed. Engage the chain brake for starting. Start the saw on firm ground, or use another starting method only if the manual permits it. Keep the bar clear of people and objects.
- Check idle. Let the saw warm as the manual directs. With the brake released and the bar clear, confirm that the chain does not creep at idle. If it moves, stop the engine and do not continue.
- Check brake action. In a clear, controlled area, hold the saw securely and point the bar away from people. Perform the brake test exactly as the MS 311 manual directs. The chain must stop promptly. Do not add throttle or alter the procedure unless the manual specifically says to.
- Stop if the result is uncertain. A slow stop, inconsistent action, unusual sound, or damaged hand guard means the saw should not be used until checked.
For cutting, release the brake only just before you begin. Use two hands, maintain stable footing, and keep the bar nose away from objects. Do not cut above shoulder height or operate the saw one-handed.
Common test results and what to do next
A failed check can point to more than one problem. For example, chain movement at idle is not proof that the chain brake has failed; it means the saw needs attention before use. Avoid trying to correct faults by changing carburetor settings or making brake repairs without the right training.
| Observation | What it may mean | Safe next step |
|---|---|---|
| Chain moves at idle with brake released | The saw is not behaving as required | Stop work; have the cause diagnosed |
| Brake does not stop the chain promptly | Brake may be damaged, dirty, worn, or incorrectly assembled | Stop using the saw; contact a STIHL service provider |
| Hand guard is cracked, loose, or obstructed | Brake operation may be affected | Do not operate until inspected |
| Brake feels inconsistent or the result is unclear | The test has not confirmed safe operation | Do not repeat risky tests; seek qualified help |
A rotational kickback can happen when the upper part of the guide-bar nose contacts an object. The saw may rotate toward the operator. A damaged, contaminated, or poorly maintained brake may not stop the chain as intended. If you suspect brake failure, do not test it in a cut. Stop using the saw and have it inspected.
Field scenarios: inspection or service?
These examples are practical situations, not reports of specific repair cases. They show how to decide whether a routine check is enough or whether the saw needs professional service. The chain brake is not a part to install or adjust by guesswork.
- After transport or storage: Inspect the hand guard and brake area for damage or debris, then complete the manual’s checks before use.
- After the saw is dropped: Do not assume the brake still works because the guard looks intact. Inspect the saw and have it checked if any part is damaged or the brake action is uncertain.
- After a failed test: Stop. Do not keep cutting or try repeated high-speed checks. Ask a STIHL dealer or qualified service provider to inspect the brake.
- When replacing a bar or chain: Confirm the bar mount, pitch, gauge, and drive-link count match an approved setup for the saw and sprocket. Correct fit does not prove the brake works, so still perform the manual’s checks.
These steps can prevent a fit problem from being mistaken for a brake problem. They do not replace professional repair. If a brake component needs removal, fitting, or adjustment, use the model-specific service information and qualified support.
Chain-brake care, shutdown, and storage
Routine cleaning and inspection help you notice problems early, but they do not make a damaged brake safe. Follow the manual for cleaning around the brake and clutch area. Do not take apart, alter, or lubricate brake parts unless the manual specifically directs you to do so.
Keep the chain sharp and correctly adjusted. The general STIHL 3/8-inch chain depth-gauge reference is 0.65 mm (0.025 in), but confirm the exact chain model’s filing instructions and use a depth-gauge tool. This measurement relates to cutting performance; it is not a chain-brake test.
After work, engage the brake and shut down as the manual directs. Let the saw cool before cleaning or refueling. Check for chain damage, looseness, debris around the brake, and signs that chain oil is reaching the bar. Oil delivery depends on conditions and saw setup, so do not rely on one universal flow amount.
For storage, clean and store the saw as directed in the manual. Before the next use, inspect it again and repeat the checks. If the brake’s performance is uncertain at any point, leave the saw off until it has been checked.
Frequently asked questions
What does the STIHL MS 311 chain brake do?
It is designed to stop the moving chain when correctly activated, including by pushing the front hand guard forward.
Should the chain move at idle?
No. With the brake released and the saw idling, the chain should remain stationary. If it creeps, stop using the saw and have it checked.
How do I test the MS 311 chain brake?
Follow the brake-check procedure in the manual for your exact saw. Do not improvise a test or use a cut to check brake action.
Can I test the brake at full throttle?
Do not perform an improvised full-throttle test. Use only the method stated in the correct MS 311 manual.
What if the brake stops the chain slowly?
Stop using the saw. A slow or uncertain stop needs inspection by a STIHL dealer or qualified service provider.
Can I adjust the idle to stop chain creep?
Do not adjust the carburetor to hide chain movement. Stop work and have the cause diagnosed.
Does a successful brake test mean the saw is safe to use?
No. You still need proper protective equipment, a pre-use inspection, safe footing, and correct saw handling.
Can I clean or repair the chain brake myself?
Clean only as the manual permits. Do not dismantle or repair brake parts unless you have the correct training and service information.
Which bar and chain fit the MS 311?
Use an approved combination for your saw, sprocket, and bar mount. Verify pitch, gauge, and drive-link count from the markings and manual.
Is the MS 311 suitable for climbing?
No. It is intended for ground-based work, such as bucking and suitable felling. Follow the manual and use equipment designed for the task.
(This article was written by one of our staff writers, Evan Bradley. Visit our Meet the Team page.)
