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Cert III Mobile Plant study materials
Cert III Mobile Plant study resources

Cert III Mobile Plant practice questions

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Question 1Core Units

Which document must be completed before a mobile plant operator begins a shift on a new work area?

  1. A copy of the manufacturer's warranty card
  2. A pre-start inspection and risk assessment of the work area Correct answer.
  3. A purchase order for replacement parts
  4. A timesheet signed by the site supervisor

Explanation

Before operating in any new area the operator must complete a pre-start inspection of the machine and assess the work area for hazards such as slopes, services and other workers. This establishes that both the equipment and the environment are safe to proceed.

Question 2Core Units

What is the main purpose of a site traffic management plan for mobile plant operations?

  1. To record the fuel consumption of each machine
  2. To schedule maintenance for the plant fleet
  3. To list the names of all plant operators on site
  4. To separate pedestrians and plant and control movement paths Correct answer.

Explanation

A traffic management plan sets out designated routes, exclusion zones, speed limits and pedestrian crossings so that people and machines are kept apart. Separation and controlled movement are the core controls that prevent run-over and collision incidents.

Question 3Core Units

An operator hears an audible travel alarm sounding continuously while reversing. What does this indicate?

  1. The reversing alarm is warning people nearby that the machine is moving Correct answer.
  2. The hydraulic system is overheating
  3. The parking brake has failed to release
  4. The engine oil pressure has dropped below safe level

Explanation

An audible travel or reversing alarm is a warning device that alerts people in the area that the machine is about to move or is moving. It is a pedestrian safety control, not an engine or hydraulic fault indicator.

Question 4Core Units

Which piece of personal protective equipment is essential when operating a mobile plant machine with an open cab?

  1. Hearing protection and a high-visibility garment Correct answer.
  2. A respirator and chemical splash goggles
  3. Anti-vibration gloves and a dust mask only
  4. A welding helmet and leather apron

Explanation

Open-cab machines expose the operator to engine and hydraulic noise and to the risk of not being seen by others, so hearing protection and high-visibility clothing are required. These match the two dominant hazards of noise and visibility.

Question 5Core Units

What should an operator do if a fault is found during the pre-start inspection?

  1. Record the fault and continue normal operation
  2. Operate the machine slowly until the end of the shift
  3. Ask a workmate to watch the faulty component while operating
  4. Tag the machine out and report the fault before use Correct answer.

Explanation

Any defect that affects safe operation requires the machine to be isolated, tagged and reported so it cannot be used until repaired. Continuing to operate a faulty machine, even slowly or with a spotter, keeps the hazard active.

Question 6Core Units

Why must an operator lower the bucket or attachment to the ground before leaving the operator seat?

  1. To allow the hydraulic oil to cool faster
  2. To reduce tyre wear during breaks
  3. To prevent unexpected movement and stored energy release Correct answer.
  4. To improve fuel efficiency while idling

Explanation

Raised attachments store potential and hydraulic energy that can cause the machine to move or the attachment to drop if controls are bumped. Lowering to the ground and isolating removes that stored energy before the operator dismounts.

Question 7Core Units

A mobile plant operator is about to work near an overhead power line. What is the safest first action?

  1. Continue working while keeping the boom low
  2. Increase engine speed to move through the area quickly
  3. Ask a workmate to watch the boom and signal
  4. Stop and confirm the exclusion distance with the supervisor before proceeding Correct answer.

Explanation

Overhead lines carry lethal voltages and plant can arc to them before physical contact, so the required exclusion zone must be confirmed before any work starts. The operator should stop and verify clearances with the supervisor rather than rely on informal controls.

Question 8Core Units

Which action best controls the risk of a machine tipping on a slope?

  1. Raising the attachment to improve visibility
  2. Travelling across the slope at an angle
  3. Increasing speed to reduce time on the slope
  4. Travelling straight up or down the slope with the load low Correct answer.

Explanation

Travelling directly up or down the fall line with the load kept low keeps the centre of gravity within the machine's stability limits. Crossing a slope or raising the load shifts the centre of gravity and greatly increases roll-over risk.

Question 9Core Units

What is the correct response when a mobile plant operator loses sight of a pedestrian spotter?

  1. Assume the spotter has moved to a safe position
  2. Continue at reduced speed using mirrors
  3. Stop the machine until contact with the spotter is re-established Correct answer.
  4. Sound the horn and keep reversing

Explanation

If the operator cannot see the spotter, the agreed signal system has failed and the operator must stop immediately. Continuing to move blind removes the only control protecting people in the blind spot.

Question 10Core Units

Which practice correctly manages fatigue during a long shift operating mobile plant?

  1. Skipping breaks to finish the task sooner
  2. Keeping the cabin warm and quiet to stay relaxed
  3. Drinking energy drinks to stay alert throughout the shift
  4. Taking scheduled breaks and reporting fatigue to the supervisor Correct answer.

Explanation

Fatigue impairs judgement and reaction time, so planned rest breaks and open reporting of fatigue are the recognised controls. Stimulants and skipped breaks mask fatigue without restoring alertness.

Question 11Core Units

What does the load chart or rated capacity plate on a mobile plant machine tell the operator?

  1. The recommended service interval for the machine
  2. The fuel tank capacity and consumption rate
  3. The maximum travel speed on public roads
  4. The maximum safe load at specified radii and configurations Correct answer.

Explanation

A load chart specifies the maximum load the machine can safely handle at given radii, boom lengths and configurations. Exceeding these limits overloads the machine and can cause structural failure or tipping.

Question 12Core Units

What is the primary reason for conducting a daily pre-start inspection of fluid levels and leaks?

  1. To record the machine's odometer for insurance
  2. To detect defects that could cause failure or environmental harm Correct answer.
  3. To confirm the operator's shift hours
  4. To calculate the machine's hourly operating cost

Explanation

Checking fluids and looking for leaks identifies defects such as low oil, coolant loss or hydraulic leaks before they cause breakdowns, fires or environmental contamination. Early detection allows repair before the fault becomes dangerous.

Question 13Core Units

When must a mobile plant operator use a seat belt in a machine fitted with a roll-over protective structure?

  1. At all times while seated in the operator position Correct answer.
  2. Only when the supervisor is present
  3. Only when travelling on public roads
  4. Only when the machine is reversing

Explanation

A seat belt keeps the operator inside the protective zone of the roll-over structure if the machine tips or impacts. It must be worn at all times the machine is operated, not only in selected situations.

Question 14Core Units

What is the correct way to communicate with a truck driver when loading from a mobile plant machine?

  1. Rely on the truck driver watching the mirrors
  2. Assume the driver knows the loading sequence
  3. Use the agreed signal system and confirm the driver is clear before loading Correct answer.
  4. Sound the horn once and load immediately

Explanation

Loading requires a pre-agreed signal system so both operators know when the truck is positioned and the driver is clear of the load zone. Confirming the driver's position before each bucket prevents crushing injuries.

Question 15Core Units

Which control is required before an operator performs maintenance on a raised hydraulic attachment?

  1. Lower the engine speed and proceed
  2. Fit a mechanical support or prop and isolate the hydraulics Correct answer.
  3. Ask a workmate to hold the control lever
  4. Rely on the hydraulic cylinders to hold the load

Explanation

Hydraulic systems can lose pressure and drop a raised attachment, so a mechanical prop or support plus isolation is required before anyone works under it. Hydraulic pressure alone must never be trusted to hold a load.

Question 16Core Units

What is the purpose of a lock-out tag-out procedure on mobile plant?

  1. To record the machine's daily production output
  2. To identify which operator is on shift
  3. To prevent unexpected energisation or movement during maintenance Correct answer.
  4. To track the machine's warranty period

Explanation

Lock-out tag-out isolates energy sources and attaches a personal lock and tag so the machine cannot be started or moved while someone is working on it. It is a personal protection control against unexpected energisation.

Question 17Core Units

A machine's horn fails during the pre-start check. How should the operator proceed?

  1. Use hand signals instead of the horn
  2. Operate the machine but avoid crowded areas
  3. Operate only in reverse so the travel alarm warns people
  4. Do not operate the machine and report the defect Correct answer.

Explanation

The horn is a primary warning device for alerting people, so a faulty horn makes the machine unsafe to operate. The machine should be tagged out and the defect reported for repair.

Question 18Core Units

Which factor most affects the stability of a telehandler when lifting a load?

  1. The load's weight and its distance from the machine Correct answer.
  2. The colour of the load being lifted
  3. The number of operators on site
  4. The age of the machine's tyres only

Explanation

Stability depends on the load moment, which is the load weight multiplied by its distance from the tipping point. Heavier loads and greater reach both reduce the margin of stability.

Question 19Core Units

An operator notices the machine's steering feels unresponsive on a haul road. What is the safest immediate action?

  1. Continue and monitor the steering until the next break
  2. Continue to the workshop at normal speed
  3. Increase engine speed to improve steering response
  4. Stop the machine in a safe location and report the fault Correct answer.

Explanation

Loss of steering response is a critical safety fault that can lead to loss of control, so the operator should stop safely as soon as possible and report it. Continuing to travel risks a collision or roll-over.

Question 20Core Units

What is the correct interpretation of a stability plate showing a reduced capacity at increased boom angle and reach?

  1. The plate applies only to stationary lifting
  2. Capacity increases as the boom extends further
  3. Capacity is constant regardless of boom position
  4. Capacity decreases as reach increases, so the load must be reduced accordingly Correct answer.

Explanation

Stability plates show that the allowable load falls as the boom is extended or lowered because the load moment increases. The operator must reduce the load to stay within the rated capacity for that configuration.

Question 21Core Units

Two machines must work in the same area. Which approach best manages the interaction risk?

  1. Allow both to operate freely and rely on operators watching each other
  2. Have one machine work only in reverse
  3. Agree on separated work zones and communication before starting Correct answer.
  4. Increase both machines' speed to reduce overlap time

Explanation

Interaction between machines is controlled by planning separate zones, agreed communication and sequencing before work begins. Relying on mutual observation or speed increases the chance of collision.

Question 22Core Units

Why is it important to check ground conditions before positioning a mobile plant machine for lifting?

  1. Soft or sloping ground can reduce stability and cause the machine to sink or tip Correct answer.
  2. Ground checks only affect tyre wear
  3. Ground colour indicates the load capacity
  4. Ground conditions are irrelevant once the outriggers are down

Explanation

The ground must bear the machine and load; soft, uncompacted or sloping ground can cause settling, outrigger penetration or tipping. Stability depends on a firm, level base as much as on the load chart.

Question 23Core Units

What should an operator do if a hydraulic hose bursts during operation?

  1. Wipe the leak and keep working
  2. Increase hydraulic pressure to compensate
  3. Continue operating until the task is complete
  4. Lower the attachment safely, stop the machine and isolate the system Correct answer.

Explanation

A burst hose releases high-pressure fluid that can cause injection injuries and loss of control, so the operator should safely lower the attachment, stop and isolate the system. Continuing to operate risks injury and further damage.

Question 24Core Units

Which record best demonstrates that a mobile plant operator has been trained for a specific machine?

  1. A general site induction card
  2. A driver's licence for a car
  3. A first aid certificate
  4. A competency or verification of competency record for that machine class Correct answer.

Explanation

Competency records, often called verification of competency, confirm that the operator has been assessed on the specific machine class. General inductions and unrelated licences do not demonstrate machine-specific competence.

Question 25Core Units

What is the operator's responsibility when a hazard cannot be controlled at their level?

  1. Stop work and escalate the hazard to the supervisor Correct answer.
  2. Proceed while wearing extra PPE
  3. Ask a workmate to take over the task
  4. Ignore the hazard if it is minor

Explanation

When a hazard exceeds the operator's authority or controls, the correct action is to stop work and escalate it so a suitable control can be implemented. Proceeding or passing the task on leaves the hazard uncontrolled.

Question 26Core Units

Which document states the legal duties of a person conducting a business or undertaking to manage risks to health and safety on a civil construction site?

  1. The site's work health and safety legislation and its associated regulations Correct answer.
  2. The supplier's delivery docket for plant hire
  3. The machine manufacturer's operator handbook
  4. The project's quality assurance inspection plan

Explanation

Work health and safety legislation and the regulations made under it set out the legal duties of the person conducting the business or undertaking, including the duty to manage risks. Manufacturer handbooks give operating guidance but do not create the statutory duty. Site plans and delivery paperwork are administrative records only.

Question 27Core Units

Under the hierarchy of control, which measure ranks highest for controlling a hazard associated with mobile plant operation?

  1. Retraining operators in safe work procedures
  2. Eliminating the hazard by removing the need for the task Correct answer.
  3. Providing personal protective equipment to the operator
  4. Placing warning signage around the work area

Explanation

The hierarchy of control ranks elimination of the hazard as the most reliable measure, because the risk is removed entirely rather than managed. Personal protective equipment, signage and retraining are lower-order controls that depend on human behaviour and only reduce residual risk.

Question 28Core Units

What is the main purpose of a safe work method statement for high-risk construction work involving mobile plant?

  1. To record the operator's hours of work for payroll purposes
  2. To list the spare parts held in the site stores
  3. To confirm the machine has passed its registration inspection
  4. To describe how the high-risk work will be done and how the risks will be controlled Correct answer.

Explanation

A safe work method statement sets out the high-risk construction work to be carried out, the hazards involved, and the control measures to be applied, and it must be reviewed and kept current. It is a risk-control document, not a payroll, stores or registration record.

Question 29Core Units

An operator is directed to perform a task that they believe is unsafe. What is the most appropriate action?

  1. Stop the task, raise the concern with the supervisor, and wait for the risk to be resolved Correct answer.
  2. Complete the task quickly so the risk exposure is brief
  3. Continue the task and report the concern at the end of the shift
  4. Ask a less experienced colleague to do the task instead

Explanation

Every worker has the right and the duty to stop unsafe work and raise the concern so the risk can be assessed and controlled. Completing the task quickly does not remove the hazard, and passing it to another worker simply transfers the risk. Reporting only at the end of the shift leaves the danger in place.

Question 30Core Units

Which document should an operator check to confirm the correct tyre pressure and torque settings for a specific machine?

  1. The manufacturer's operation and maintenance manual for that machine Correct answer.
  2. The project's emergency evacuation plan
  3. The operator's competency card
  4. The site induction booklet

Explanation

The manufacturer's operation and maintenance manual contains the machine-specific specifications, including tyre pressures and torque values. Site induction material, emergency plans and competency cards deal with other matters and do not carry technical specifications.

Question 31Core Units

What does a traffic management plan primarily control on a construction site with mobile plant?

  1. The disposal of general waste
  2. The separation of pedestrians and vehicles and the movement routes for plant Correct answer.
  3. The roster of crane operators
  4. The ordering of concrete deliveries

Explanation

A traffic management plan sets out routes, exclusion zones, pedestrian separation and speed limits so that people and plant can move safely. It does not manage delivery scheduling, operator rosters or waste disposal, which are separate site functions.

Question 32Core Units

Which item of personal protective equipment is most important when an operator must leave the cab to inspect a machine on a busy site?

  1. A tool belt for carrying spanners
  2. Ear plugs for noise reduction
  3. A dust mask for respiratory protection
  4. A high-visibility garment that makes the person conspicuous to plant operators Correct answer.

Explanation

When a person leaves the cab near moving plant, being seen is the critical control, so high-visibility clothing is essential. Dust masks, hearing protection and tool belts serve other purposes and do not prevent a collision with a machine.

Question 33Core Units

What is the correct action when an operator finds a defect on a machine during the pre-start check that could affect safe operation?

  1. Note the defect and continue until the next scheduled service
  2. Tag the machine out of service and report the defect to the supervisor Correct answer.
  3. Ask another operator whether the defect is serious
  4. Record the defect and operate the machine at reduced speed

Explanation

A defect that could affect safe operation must be isolated by tagging the machine out of service and reported so it can be repaired and inspected. Operating at reduced speed or deferring repair leaves a known hazard active, and another operator's opinion is not a substitute for the defect procedure.

Question 34Core Units

An operator is about to reverse a haul truck in a busy loading area. Which combination of actions best manages the blind spot?

  1. Rely on the reversing camera alone and reverse at normal speed
  2. Reverse quickly to reduce the time spent in the hazard zone
  3. Confirm the area is clear using mirrors and a spotter, sound the reversing alarm, and reverse slowly Correct answer.
  4. Ask a nearby worker to wave the truck through without a briefing

Explanation

Blind spots are best managed by combining checks of the area, a trained spotter, an audible reversing alarm and a slow reversing speed so the operator can stop if anything appears. Reversing quickly or relying on one device alone leaves gaps in the control.

Question 35Core Units

Which practice best protects the operator when entering and exiting a machine cab?

  1. Carry tools in both hands to save trips
  2. Use the handrails only when the steps are wet
  3. Jump from the last step to reduce time at the machine
  4. Maintain three points of contact and face the machine while climbing Correct answer.

Explanation

Maintaining three points of contact and facing the machine keeps the body balanced and supported, which is the standard control against slips and falls from height. Carrying loads in the hands, jumping down or using handrails only in wet weather all remove that support.

Question 36Core Units

A mobile plant machine will be operated in an area where an excavator is also working. Which control best prevents a collision between the two machines?

  1. Define and enforce exclusion zones and agreed travel routes for each machine Correct answer.
  2. Rely on each operator to watch for the other machine
  3. Sound the horn continuously while operating
  4. Operate both machines only during daylight hours

Explanation

Physical separation through defined exclusion zones and agreed travel routes is the most reliable control because it removes the chance of the machines meeting. Relying on operators watching for each other depends on attention and line of sight, and horns or daylight do not prevent collisions.

Question 37Core Units

What is the main reason for conducting a site-specific risk assessment before operating mobile plant in a new area?

  1. To identify local hazards and confirm controls before work begins Correct answer.
  2. To determine the hire cost of the machine
  3. To calculate the operator's productivity rate
  4. To satisfy the machine's service schedule

Explanation

A site-specific risk assessment identifies the hazards particular to the new area, such as ground conditions, services and other trades, and confirms that suitable controls are in place before work starts. It is not a servicing, productivity or costing exercise.

Question 38Core Units

Which environmental control is most appropriate when refuelling a mobile plant machine on site?

  1. Wash any spilled fuel into the stormwater drain
  2. Refuel over bare soil so the fuel soaks away
  3. Leave the fuel nozzle unattended to speed up filling
  4. Use a bunded area or spill kit and prevent fuel from reaching drains Correct answer.

Explanation

Refuelling must be done where spills can be contained, using bunding or a spill kit, and fuel must be kept out of drains and waterways. Washing fuel into a drain, leaving the nozzle unattended or letting fuel soak into soil all cause environmental harm.

Question 39Core Units

What is the primary purpose of a plant hazard and risk register maintained on a construction site?

  1. To record the fuel consumption of each machine
  2. To list the names of all plant operators on site
  3. To record identified plant hazards, the associated risks and the controls applied Correct answer.
  4. To track the delivery dates of plant equipment

Explanation

A plant hazard and risk register documents the hazards associated with plant, the assessed risk and the controls in place, so that risks can be monitored and reviewed. Operator names, fuel use and delivery dates are separate records.

Question 40Core Units

An operator is required to work at night. Which control most directly maintains visibility of pedestrians around the machine?

  1. Reduced engine speed to lower noise
  2. Adequate task lighting and high-visibility clothing with reflective material Correct answer.
  3. Additional ballast on the machine
  4. Tighter turning circles

Explanation

Night work reduces natural visibility, so task lighting and reflective high-visibility clothing are the direct controls that let the operator see pedestrians and be seen by them. Engine speed, ballast and turning circles affect performance or stability but not visibility.

Question 41Core Units

Which behaviour best demonstrates an operator's duty to work safely without affecting others?

  1. Following site procedures and reporting hazards even when unsupervised Correct answer.
  2. Using a mobile phone while the machine is moving
  3. Removing guards to speed up a maintenance task
  4. Allowing passengers to ride on the machine outside the cab

Explanation

Working safely without supervision means applying procedures consistently and reporting hazards so others are protected. Using a phone while operating, carrying unauthorised passengers or removing guards all create risks for the operator and others.

Question 42Core Units

What is the correct way to park a mobile plant machine at the end of a shift on a level site?

  1. Lower the attachment, apply the park brake, isolate the machine and remove the key Correct answer.
  2. Park with the attachment raised to keep it clear of the ground
  3. Leave the engine running so the machine is ready for the next shift
  4. Leave the transmission in neutral without the park brake

Explanation

A machine is left safe by lowering the attachment, applying the park brake, isolating the machine and removing the key so it cannot be started or move unexpectedly. Leaving the engine running, the attachment raised or the transmission in neutral without the brake creates hazards.

Question 43Core Units

Which record is the best evidence that an operator has been assessed as competent on a particular type of mobile plant?

  1. A driver's licence for a car
  2. A first aid certificate
  3. A general site induction certificate
  4. A current competency assessment or verification of competency for that plant type Correct answer.

Explanation

Competence on a particular plant type is demonstrated by a current competency assessment or verification of competency that names that machine type. A site induction, first aid certificate or car licence does not show plant-specific skill.

Question 44Core Units

A mobile plant operator hears an unfamiliar noise from the transmission during operation. What is the most appropriate response?

  1. Stop the machine in a safe place, isolate it and report the fault for inspection Correct answer.
  2. Continue operating until the next scheduled service
  3. Ignore the noise if the machine still moves normally
  4. Increase engine speed to clear the noise

Explanation

An unfamiliar noise can indicate a developing mechanical failure, so the operator should stop safely, isolate the machine and report it for inspection before further use. Increasing speed, deferring to the next service or ignoring the noise risks a breakdown or loss of control.

Question 45Core Units

Which factor most directly determines the minimum separation distance an operator must keep from an excavation edge?

  1. The colour of the machine
  2. The time of day the work is done
  3. The operator's years of experience
  4. The ground conditions and the load imposed by the machine near the edge Correct answer.

Explanation

Separation from an excavation edge is governed by the stability of the ground and the load the machine places on it, because a surcharge near the edge can cause the face to collapse. Machine colour, experience and time of day do not determine the required distance.

Question 46Core Units

An operator must lift a load with a machine whose load chart shows a capacity that decreases with radius. What is the correct approach?

  1. Determine the load weight and radius first and confirm the capacity is not exceeded before lifting Correct answer.
  2. Add a safety margin by lifting the load at a longer radius
  3. Estimate the load weight by eye and lift slowly
  4. Use the maximum capacity shown on the chart regardless of radius

Explanation

Capacity falls as radius increases, so the operator must know both the actual load weight and the working radius and confirm the chart capacity is not exceeded before lifting. Estimating by eye, using the maximum figure or increasing the radius all risk overloading and tipping.

Question 47Core Units

A worker is struck by a reversing machine on site. Which action should the operator take first?

  1. Stop the machine, isolate it and raise the alarm to summon emergency help Correct answer.
  2. Continue working to keep the site schedule
  3. Move the machine forward to free the worker
  4. Complete an incident report before helping

Explanation

The first priority is to stop and isolate the machine so it cannot move again, then raise the alarm and summon trained emergency help for the injured person. Moving the machine, filling in paperwork first or continuing work can worsen the injury and delay treatment.

Question 48Core Units

Which analysis best explains why a machine with a raised loaded boom is less stable than the same machine with the boom lowered?

  1. Raising the load reduces the hydraulic fluid level
  2. Raising the load reduces the machine's engine power
  3. Raising the load increases the tyre pressure
  4. Raising the load raises the centre of gravity and moves it closer to the tipping line Correct answer.

Explanation

A raised load lifts the combined centre of gravity and shifts it toward the tipping line, which reduces the margin before the machine becomes unstable. Engine power, tyre pressure and hydraulic fluid level do not explain the change in stability.

Question 49Core Units

An operator is asked to use a machine for a task outside the manufacturer's stated purpose. What is the most appropriate response?

  1. Decline until a risk assessment and engineering approval confirm the task is safe Correct answer.
  2. Modify the machine to suit the task without approval
  3. Proceed because the supervisor has requested it
  4. Attempt the task and stop if the machine feels unstable

Explanation

Using plant outside its designed purpose requires a documented risk assessment and engineering approval before work begins, because the manufacturer's limits define safe use. Attempting the task, relying on the supervisor's request or making unauthorised modifications can cause failure or injury.

Question 50Core Units

Which control best manages the risk of a mobile plant machine contacting buried services during excavation?

  1. Assume services run in straight lines between pits
  2. Dig quickly to reduce the time near the service
  3. Rely on the operator to feel resistance through the controls
  4. Obtain service plans, use a locating service and pothole by hand before machine digging Correct answer.

Explanation

Buried services are managed by obtaining plans, having them located and confirming their position by careful hand potholing before machine digging begins. Feeling resistance, digging quickly or assuming straight runs are unreliable and can strike a service.