Safety & Compliance · SOP

Heavy Equipment Lockout Tagout (LOTO) for Engine Servicing

This SOP describes the mandatory step-by-step procedure for isolating and locking out all energy sources on heavy equipment (excavators, loaders, dozers, etc.) before performing engine servicing tasks. Adherence prevents accidental startup, release of stored energy, and serious injury.

Estimated Time

30 min

Difficulty

Intermediate

Regulation

CSA Z460

Version

1.0

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Purpose

To provide a standardised, controlled method for de-energising and locking out all energy sources on heavy equipment prior to engine servicing. This procedure ensures personnel are protected from unexpected energisation, startup, or release of stored energy that could cause serious injury or death.

Scope

Applies to all maintenance personnel, mechanics, and technicians performing any engine-related service (oil change, belt replacement, injection pump work, turbocharger service, etc.) on heavy equipment in the shop or field. Includes diesel engines, gas engines, and hybrid/electric drive systems where auxiliary energy sources exist.

Safety Precautions

LOTOOnly authorized personnel trained in lockout/tagout (CSA Z460) may perform this procedure. Each worker must apply their own personal lock and tag.
PPEWear safety glasses, hearing protection (if engine is running during verification), cut-resistant gloves, and steel-toed boots. Use insulated tools when verifying electrical circuits.
STORVerify that all stored energy (hydraulic accumulators, compressed air, capacitors, springs) has been released or blocked before touching any components.
TESTAlways attempt a start (without damaging equipment) after locks are installed to confirm zero energy state. Do not rely solely on gauges.

Required Tools & Materials

Lockout kit: padlocks (keyed differently per worker), hasps, lockout tags, and identification labels
Group lockout box (if multiple workers)
Voltage/continuity tester (rated for system voltage)
Hydraulic pressure gauge and bleed kit
Insulated screwdrivers and wrenches
Lockout logbook or digital form
Machine-specific service manual

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Procedure: Step-by-Step

1 Identify all energy sources. Consult the machine’s service manual. List all electrical, hydraulic, pneumatic, kinetic (fan blades, flywheels), thermal, and potential (gravity) energy sources. Document them on the lockout tag/lockout log.

2 Notify affected personnel. Inform operators, supervisors, and other workers in the vicinity that a lockout is in progress and that the machine is to be shut down for servicing. Post warning signs if necessary.

3 Shut down the engine. Turn the ignition key to OFF and remove it. For keyless systems, follow manufacturer’s shutdown procedure (e.g., hold stop button 3 seconds). Wait for all moving parts to come to a complete stop.

4 Isolate and lock out all disconnect switches and valves. Locate the main battery disconnect, master electrical switch, hydraulic shut-off valves, fuel shut-off, and any other isolation points. Install a lockout hasp and your personal padlock on each. Do not use a single lock for multiple isolation points.

5 Release all stored energy. Bleed hydraulic accumulators by following the machine-specific procedure (often via a bleed screw). Discharge capacitors (if applicable) using a safe discharge tool. Release any compressed air or spring tension. Visually confirm that all potential energy is zero.

6 Verify zero energy state. Using a voltage/continuity tester, check all electrical circuits (battery cables, control modules) for absence of voltage. Attempt to start the engine using the normal start mechanism (key or button) – the engine must not crank. For hydraulic systems, activate a control lever; no movement should occur.

7 Attach personal lock and tag. Each maintenance worker performing service must place their own lock and a filled-out tag on each isolation point (or on the group lockout box if using a group system). The tag must include: worker name, date, estimated duration, and reason for lockout.

8 Proceed with engine servicing. Only after verification is complete may service work begin. Keep the key or start interlock in a secure location under the lockout custodian’s control.

9 Removal of locks and restoration. When work is complete, each worker removes their own lock and tag. The final check involves verifying that all tools and debris are clear, all guards replaced, and that no personnel are in the danger zone. Restore the machine to service: close isolation valves, reconnect battery, bleed hydraulic lines if needed, and perform a test run from a safe location.

Heavy Equipment Lockout Tagout (LOTO) for Engine Servicing

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