Mobile Plant
pre-use check

The 15 things to look at before the key turns on excavator / digger, telehandler, dumper, roller / compactor, forklift.

Every item below says what good looks like, when it passes, the regulation or manufacturer's standard it rests on and the defects that usually fail it. That guidance is the difference between a tick and a check.

1. 1.

   Walk-around visual check — no damage or leaks
   What to look forA complete 360° walk before start-up. Check for fresh oil/diesel/coolant patches under the machine, dents or cracks in the chassis, missing fasteners on covers and panels, loose pins on linkages, damaged glass, missing ROPS/FOPS plates, and any informal repairs (welds, cable-ties, duct-tape) that suggest hidden damage. Look up at the cab structure as well as down at the ground.
   Acceptable whenNo fluid pooling on the ground after overnight stand. ROPS/FOPS plate present, legible, and not modified. No cracked welds, no panels missing or held on with cable ties. All decals (SWL, controls, warning) legible.
   StandardPUWER 1998 reg.5 & reg.6 (suitability and maintenance). ROPS to ISO 3471, FOPS to ISO 3449. Manufacturer's daily walk-around in the operator's handbook.
   Common defectsFresh oil drips under the engine bay — usually rocker cover gasket or sump plugCracks at the boom-to-chassis weld — stop and refer to fitterROPS plate missing or drilled through (e.g. for an aerial mount) — the cab is no longer certifiedStowage box hanging by one bracket — debris fall hazardMud build-up around tracks/rams hiding leaks and damage
2. 2.

   Engine oil level correct
   What to look forMachine on level ground, engine off and cold (or per handbook), dipstick wiped, reinserted fully and read. Oil should sit between MIN and MAX, be amber to dark brown, free-flowing on the dipstick. No metallic glitter, no creamy emulsion (head-gasket / coolant ingress), no diesel smell (fuel dilution).
   Acceptable whenLevel between MIN and MAX marks (or within the cross-hatched section). Manufacturer's grade as stamped on the filler cap (commonly 15W-40 for plant diesels, 10W-30 in low-temp territory). No external weeping at sump plug or filter.
   StandardPUWER 1998 reg.6. Manufacturer's daily check schedule. Oil grades to ACEA E7/E9 or API CJ-4/CK-4 for modern diesels.
   Common defectsReading taken on a slope — false low or highCreamy/milky oil on the dipstick — coolant in the oil, do not startStrong diesel smell — injector seal failure diluting the sumpBlack sooty oil only days after a service — clogged DPF or stuck EGRWrong grade topped up — common when a generic 5L can is left on the truck
3. 3.

   Coolant level correct
   What to look forCheck the expansion tank only when COLD — never unscrew a hot pressure cap. Level should be between MIN and MAX; coolant a clean colour (typically pink, blue, or green depending on OAT/HOAT/IAT spec). No oil film floating on top, no rust-coloured staining, no air bubbles when the engine is running.
   Acceptable whenBetween MIN and MAX cold. Mixture 50/50 antifreeze:water (or as per handbook) giving protection to approx -36°C. Cap seals firmly, no white crystalline deposits round the neck.
   StandardPUWER 1998 reg.6. Manufacturer's coolant spec (e.g. CAT ELC, JCB Premium Antifreeze). BS 6580 / ASTM D3306 base specification.
   Common defectsOil floating on top of the coolant — head gasket or oil-cooler failureRust-coloured coolant — long overdue for a flush, internal corrosionTopped up with plain water — protection level reduced, freeze riskAir bubbles when running — combustion gases entering the cooling systemSweet smell round the engine bay — pinhole leak in a hose or radiator core
4. 4.

   Hydraulic fluid level correct
   What to look forSight glass shows fluid in the green band, or dipstick reads between MIN and MAX with the cylinders fully retracted. Fluid is clear amber, not milky (water contamination) or burnt (heat damage). No leaks visible from hoses, fittings, or cylinder seals.
   Acceptable whenPer manufacturer spec — typically MAX with all rams retracted, MIN never to be below the marked low. Fluid colour amber/clear (ISO grade per machine handbook). No visible drips on the ground after 5-min idle.
   StandardPUWER 1998 reg.5 (suitability) and reg.6 (maintenance). Manufacturer's daily check schedule. ISO 11158 hydraulic fluid spec where named.
   Common defectsReading taken with rams extended — fluid level appears low when it isn'tMilky fluid — water ingress through breather or contaminated top-upBurnt smell or dark fluid — overheating, often from blocked return filterSlow weeping at hose fittings — pre-failure, replace before next shiftTop-up done with wrong grade — viscosity mismatch causes slow operation when cold
5. 5.

   Tyres / tracks condition acceptable
   What to look forTyres: tread depth, sidewall cuts, embedded steel/glass, valve cap fitted, even wear pattern. Tracks: rubber tracks for cuts and chunking; steel tracks for missing or loose bolts on shoes, cracked links, sag (deflection between idler and roller), worn sprocket teeth (sharp/hooked profile = nearing replacement).
   Acceptable whenPneumatic tyres above 1.6mm tread (legal min for vehicles; plant manufacturer often specifies higher). Steel track sag typically 25–40mm at the centre carrier roller — confirm against handbook. Rubber tracks: no exposed cords, cuts <50mm, lugs >50% original height.
   StandardPUWER 1998 reg.5. Road Vehicles (Construction & Use) Regs 1986 reg.27 for road-going tyres. Manufacturer's tension/sag spec for tracks.
   Common defectsSidewall bulge — internal cord damage, replace immediately, do not patchTrack tension too tight — accelerated wear on rollers, idlers, sprockets, and final driveTrack tension too loose — risk of de-tracking on slewSprocket teeth hooked rather than symmetrical — sprocket and chain due as a setMismatched tyre pressures left/right on a telehandler — affects fork level and stability
6. 6.

   Lights and beacons working
   What to look forWalk round with another operator confirming each lamp: side lights, dip and main beam, work lights front and rear, hazards, indicators, brake lights, amber rotating/flashing beacon. Lenses clear (not yellowed or cracked), seals intact, no condensation inside.
   Acceptable whenAll lamps function. Beacon visible 360° from the cab area. Work lights aimed to illuminate the working radius without dazzling other operators. Lens cracks ≥3mm or any water ingress = replace.
   StandardPUWER 1998 reg.5. CDM 2015 reg.13 (welfare and safe place of work). Road Vehicles Lighting Regs 1989 if travelling public roads.
   Common defectsBeacon spinning but no light — bulb gone, carrier still rotatingCracked lens with water inside — corrosion has already started, intermittent failure imminentLED panel with dead segments — reduced output, often replaced as a unitEarth strap corroded — flickering lights, especially after pressure-washingReversing light wired to side-light circuit on a hire repair — fails the check on intent
7. 7.

   Reversing alarm / camera working
   What to look forSelect reverse — alarm sounds clearly above ambient site noise. White-noise/broadband (squawker) alarms preferred on busy sites — directional and easier to localise than tonal beepers. Camera screen shows a clear image with no dead pixels, lens clean and unobstructed, infrared illumination active in low light.
   Acceptable whenAlarm audible at 5m above background. Camera image refresh rate fluid (not stalling). Screen visible in direct sunlight. View covers the rear blind spot to ground level immediately behind the machine.
   StandardCDM 2015 reg.27 (traffic routes). HSG144 The safe use of vehicles on construction sites. PUWER 1998 reg.17 (controls and warning devices). ISO 9533 audible warning systems.
   Common defectsAlarm muffled or quieter than spec — mud/debris packed into the coneCamera lens fogged — silicone seal failed, replace housingScreen black on selecting reverse — fuse blown or harness disconnect at the boom pivotTonal beeper drowned out by other site plant — switch to broadbandCamera angle knocked out of alignment — view no longer covers ground at the back
8. 8.

   Horn working
   What to look forPress from the operator's seated position. Single clear blast, audible across the working area. No need to press multiple times to get a response. Switch returns positively without sticking.
   Acceptable whenAudible from 25m in normal site conditions. Single press = single sound. No corrosion at the contact.
   StandardPUWER 1998 reg.17. CDM 2015 reg.13. Manufacturer's daily check.
   Common defectsWeak or wavering tone — diaphragm corrosion or low voltage at the hornStuck button after pressure-washing — water ingress under the dashAir horn condensate freezing in cold weather — drain trap blockedWired into a circuit that drops out under load — battery/charging issue, not horn
9. 9.

   Mirrors clean and adjusted
   What to look forAll mirrors present (typically main left, main right, kerb/close-proximity, rear). Glass clean, not chipped or de-silvered. Mounts firm — no vibration loosening at the ball joint. Adjusted from the seated position to cover the blind spots required for the machine's blind-spot diagram.
   Acceptable whenCoverage matches the manufacturer's blind-spot diagram (ISO 5006 / ISO 14401). No more than a 1m blind area at the rear/sides at ground level once mirrors and camera are combined.
   StandardISO 5006 (operator visibility for earth-moving). ISO 14401 (telehandler visibility). PUWER 1998 reg.17. CDM 2015 reg.27.
   Common defectsMirror cracked but still mounted — distorted view, replaceHeated mirror element failed — fogs in cold/wet conditionsLoose at the arm — drops out of position when boom is workedAdjusted for a different operator and not reset — common on shared plantConvex glass replaced with flat — wider blind spot than the design
10. 10.

    Seatbelt functional
    What to look forBelt webbing free of fraying, cuts, or chemical staining. Buckle clicks home positively and releases cleanly. Inertia reel locks under sharp pull. Anchor bolts torqued and not corroded. Date label still legible (where fitted).
    Acceptable whenNo fraying or cuts in the webbing. Buckle latches first time. Inertia reel locks reliably. Anchorages secure. If fitted with a presence sensor, the warning extinguishes when belted.
    StandardPUWER 1998 reg.5. CDM 2015 reg.27. Manufacturer's spec — most modern plant has a 10-year webbing life. ROPS-fitted machines (ISO 3471) require seatbelt to retain the operator within the protective zone.
    Common defectsWebbing frayed at the buckle stalk where it rubs the seat frameBuckle won't latch first time — debris or grit in the catchInertia reel sluggish — mounting bracket corrosion has tilted the reelBelt left looped behind the seat back — seat sensor bypass, common dodgeWebbing date plate beyond 10 years — replace as a unit
11. 11.

    Controls operating correctly
    What to look forEach lever, joystick, and pedal returns to neutral cleanly when released. No drift on the joystick (machine creeps with hands off). Drive pedals proportional, not on/off. Dipper, bucket, slew respond smoothly and do not "judder". Auxiliary aux/hammer circuits operate when selected. Safety lever / lockout works — when raised, controls are dead.
    Acceptable whenAll functions operate per handbook. Joysticks self-centre. No creep on neutral. Lockout/safety lever isolates all hydraulic functions.
    StandardPUWER 1998 reg.14, reg.15, reg.17 (controls, stop, warning). Manufacturer's function check. ISO 10968 (earth-moving controls).
    Common defectsJoystick drifts off-centre — wear in the gimbal, common on older machinesSlew juddery — slew brake worn or hydraulic motor leaking internallyAux circuit not picking up — solenoid valve sticking or coil failedSafety lever does not isolate — pilot valve failure, immediate critical defectPedal sticking partly on — return spring corroded, runaway risk on travel
12. 12.

    Brakes tested — service and parking
    What to look forService brake: machine stops in a straight line without grabbing or pulling, pedal feel firm not spongy. Parking brake: holds the machine on the steepest slope on site without the service brake applied, including with a typical load. Test before leaving the parking spot, not at speed in the work area.
    Acceptable whenManufacturer's stopping distance from rated travel speed on level ground. Parking brake holds on the gradient stated in the handbook (commonly 25–30% for site dumpers, less for road haulers). No pulling, juddering, or pedal fade.
    StandardPUWER 1998 reg.15 (stop controls). Construction & Use Regs reg.18 for road-going. Manufacturer's spec.
    Common defectsSpongy pedal — air in the brake lines or low fluidParking brake holds level but slips on a slope — drum/disc glazed or cable stretchedPulling left or right — uneven pad wear or seized caliperService brake fade after several stops — overheating, often fluid past its lifeInching pedal not separating drive from brake on a forklift/dumper — accelerated brake wear
13. 13.

    Fire extinguisher present and in date
    What to look forMounted in its bracket, accessible from the cab door. Pressure gauge needle in the green. Pin and tamper seal intact. Service tag stamped within the last 12 months. Body free of dents and corrosion. Hose and horn (CO₂) clear.
    Acceptable whenAnnual service in date (within 12 months). Gauge in green. Seals intact. Type and size appropriate for plant — typically 2kg dry powder or 2L wet chemical for diesel plant; AFFF for cab class A risk.
    StandardBS 5306-3 (commissioning and maintenance of extinguishers). BS 5306-8 (selection and installation). Regulatory Reform (Fire Safety) Order 2005. Manufacturer's plant fire-suppression spec.
    Common defectsService tag expired — common on long-term hireGauge in the red zone — pressure lost, will not discharge at full reachBracket vibration-loosened — extinguisher rolling around the cab floorPin seal broken without discharge — assume tampered, replaceBody corrosion at the base ring — pitted, no longer pressure-rated
14. 14.

    LOLER certificate current (if lifting)
    What to look forFor machines used to lift loads (excavator with hook, telehandler, forklift) — the thorough examination report must be in date. Certificate accessible (cab document holder or digital). Dates: last exam, next due. Examiner name and competent-person status. Equipment description matches the machine's serial/PIN. Any defects noted as rectified.
    Acceptable when6-monthly examination if lifting persons or accessory used for lifting persons; 12-monthly otherwise (or per scheme of examination). Cert in date, no outstanding defects, machine matches by serial/PIN. SWL/RCI matches the cert.
    StandardLOLER 1998 reg.9 and reg.10 (thorough examination). Schedule 1 for the report content. INDG422 HSE guidance.
    Common defectsCert in date but for a different machine — paperwork mix-up on hireMissing pages of the report (defects schedule) — incomplete, treat as expiredDefects flagged "to be rectified by [date]" — date passed, no evidence of fixExcavator used as a crane without quick-hitch certified for lifting — not covered by the certTelehandler attachment (jib, basket) has its own cert — operator only carries the machine cert
15. 15.

    Operator card / licence checked
    What to look forPhoto card matches the operator. Category endorsed for the actual machine (e.g. CPCS A12 for 360° tracked above 10t, A17 for compact). In-date — cards expire. Logbook (if blue card) entries showing experience. NPORS/CPCS verifiable on the scheme app or QR code where present.
    Acceptable whenIn-date scheme card (CPCS, NPORS, IPAF, or equivalent) for the specific category. Photo matches. For a Trained Operator (red) card — additional supervision required and logged.
    StandardCDM 2015 reg.15 (information, instruction, training). PUWER 1998 reg.9 (training). Build UK / Major Contractors Group rules where applicable.
    Common defectsCard in date but wrong category — common with telehandlers (A17 vs A77)Red trained operator card without the supervisor sign-off in the logbookCard expired in the last 30 days — operator unawarePhoto mismatch — card belongs to a workmate ("I've forgotten mine today")No card at all — operator claims long experience, no formal qualification

Questions people ask