Grizzly Screen Maintenance: The Complete Checklist

Why Grizzly Maintenance Matters

A grizzly screen at a primary scalping station is one of the highest-impact assets on the plant. When it works, it offloads 15–35% of the feed away from the jaw crusher, extends jaw plate life, reduces fuel burn, and lifts overall plant throughput. When it fails, the plant either stops or runs every ton of dirt and fines through the crusher chamber — destroying jaw plates, wasting fuel, and stockpiling expensive wear-part consumption.

The unique thing about a grizzly is that it sits at the very front of the plant. There is no upstream buffer to absorb a stoppage. Every minute the grizzly is down is a minute the entire downstream train is starved or backed up. That makes preventative maintenance not just a cost-control measure but a throughput multiplier.

Daily Checklist (Every Shift)

Daily checks are visual and audible. They take 10–15 minutes and should be done at shift handover with the machine running, then again with the machine stopped.

With the machine running

• Listen for unusual noise. A healthy grizzly produces a steady, even drone. Knocking, grinding, squealing, or rhythmic thumping are all warning signs — investigate before the next shift change.
• Watch the deck. Material should flow evenly across the full width of the deck. Channeling on one side, a static patch in the middle, or material backing up at the feed end all indicate problems.
• Check bypass flow. The amount of fines dropping through the bars should look consistent with previous shifts. A sudden drop in bypass volume usually means blinded bars.
• Check the discharge. Oversize discharge should be clean — no small material slipping through onto the oversize belt indicates broken or missing bars.
• Watch for excess vibration at the support frame. Bolt rattle, visible frame deflection, or dust shaking off the support beams all indicate spring or mounting problems.

With the machine stopped (locked out)

• Walk the deck. Look for trapped tramp metal between bars, wedged stones, blinded gaps, bent bars, or any bar that has shifted out of position.
• Clear blinded bar gaps. Pry out any wedged stones or trapped metal using a manganese pry bar. Never use a steel bar — it can damage the manganese deck bars.
• Check the feed chute. Look for accumulated build-up at the discharge of the feeder, which can change the feed pattern onto the grizzly.
• Visual bolt check. Walk around the screen and visually scan spring mounts, bar bolts, and motor base bolts for any obvious looseness or missing hardware.
• Log the bypass tonnage. If the plant has weighing on the bypass stream, log the percentage. A drifting baseline indicates a slowly developing problem.

Weekly Checklist

Weekly tasks take 60–90 minutes and require the machine locked out. Schedule them at the regular weekly maintenance window.

• Bolt torque check on bar fastenings. Spot-check a minimum of 25% of the deck bar bolts using a calibrated torque wrench. Re-torque to manufacturer spec. New screens or screens with recently replaced bars need 100% checks for the first three weeks until bolts have settled.
• Bolt torque check on motor base. The exciter motors generate high cyclic forces and motor base bolts loosen faster than anywhere else on the machine. Check 100% every week.
• Spring inspection. Visually inspect each suspension spring for cracks, sagging, or loss of preload. Measure the free length of one spring per corner and compare to the as-new dimension. Springs that have lost more than 5 mm of free length should be flagged for replacement at the next quarterly window.
• Bearing temperature reading. Run the machine to operating temperature, then take a non-contact infrared reading at each bearing housing. Log the reading. A trending increase week-over-week is the earliest warning of bearing distress.
• Lubrication system check. Verify that the auto-lube reservoir is at the correct level, the line pressures are normal, and each bearing point is showing fresh grease at the seal weep point.
• Drive belt inspection (if belt-driven). Check tension, look for cracks or glazing, verify alignment.
• Side plate inspection. Look for cracks at weld toes, particularly around the spring mount brackets and motor mounts. Mark any cracks with paint and watch them; a growing crack needs immediate repair.
• General clean-down. Remove accumulated dust and material from under the deck, around the springs, and on top of the motor housings.

Monthly Checklist

Monthly maintenance takes 3–4 hours and aligns with a planned monthly shutdown window. This is where wear measurement and trend analysis happen.

• Measure bar wear. At three points along each bar (feed end, middle, discharge end), measure the bar height with calipers. Compare to last month's readings to calculate wear rate. Use the wear rate to forecast the replacement date.
• Measure spacing uniformity. Check the bar-to-bar gap at three points along the deck. Variation of more than ±5 mm from nominal indicates that bars are shifting and the bolts may need re-torque or replacement.
• 100% bolt torque check. Every bolt on the deck — bar bolts, spring mounts, motor mounts, side plate fasteners, feed-end and discharge-end hardware — checked with a calibrated torque wrench.
• Vibration analysis. If the plant has a vibration analyzer (handheld accelerometer), record the displacement amplitude at each corner of the deck and the orbit shape at the centerline. Compare to the baseline taken at commissioning. Significant deviation indicates spring fatigue, bearing wear, or eccentric weight imbalance.
• Grease sampling. Pull a small grease sample from one bearing housing each month (rotate housings month-to-month). Visual check for metal particles, water, or discoloration. Send to a lab for analysis quarterly if the plant has the program.
• Electrical inspection. Check motor terminal box for moisture ingress, verify cable strain relief, measure motor insulation resistance with a megger if hours warrant.
• Replace any flagged bars. Bars identified as worn, bent, or cracked at any earlier inspection should be replaced now.
• Photograph the deck. Take photos of the full deck from directly above. Comparing photos month-to-month is the easiest way to spot gradual changes in the deck condition.

Quarterly Checklist

Quarterly tasks need a longer planned shutdown — typically a half-shift or one full shift. They cover the items that don't degrade on a monthly cycle but do need a scheduled inspection.

• Spring set inspection (full). Remove deck access panels and inspect each spring closely with a flashlight. Look for cracked coils, corroded surfaces, broken pigtails, or loose retainer hardware. Replace any spring showing damage. Springs are sold as matched sets — never replace just one spring on a corner.
• Bearing oil/grease change. Drain old grease or oil from each bearing housing and refill with fresh manufacturer-spec lubricant. This is also the moment to inspect the seals for wear and replace them if needed.
• Side plate weld inspection. Magnetic particle or dye penetrant inspection of the high-stress weld zones on the side plates — particularly around the spring mounts, vibrator mounts, and corner reinforcements.
• Bar set rotation (if quarter-turn bars). If using quarter-turn-capable manganese bars, rotate each bar 90° to expose a fresh wear face. This single task can extend bar life by 30–50%.
• Eccentric weight verification. Open the exciter housings, verify the weights are in their commissioned positions, check torque on the weight retainers, and confirm no weights have shifted.
• Drive coupling inspection (if cardan-driven). Check universal joint condition, slip joint lubrication, and bolt torque on the flanges.
• Spare parts inventory check. Verify that the spare parts kit (see below) is complete and replace any items used during the previous quarter.

Annual Checklist

The annual shutdown is the moment for a top-to-bottom rebuild assessment. Plan for a 1–3 day window depending on findings.

• Full bar set replacement (planned). Even if individual bars are still serviceable, plan to replace the entire bar set on an annual cycle to avoid running into a forced changeout during peak season.
• Bearing replacement decision. Based on hour count, vibration trend, and grease analysis, decide whether to replace exciter bearings during the annual window or to defer to next year. Bearing failure under load is the worst grizzly failure mode, so err toward replacement once you cross 6,000 operating hours.
• Spring set replacement (decision point). Suspension springs typically last 18–36 months. Replace the full set if any springs are flagged from quarterly inspections or if the set has more than 24 months of service.
• Deck repaint or repair. Strip flaking paint, treat any surface rust, repaint with industrial enamel. Inspect all wear plate liners and replace any that have worn through.
• Feed and discharge chute rebuild. Wear plates in the feed chute and the discharge bypass chute typically need replacement at the annual shutdown.
• Documentation update. Update the maintenance log book with running hours, parts replaced, baseline readings, and any modifications. The log book is the basis for the next year's maintenance plan.

Troubleshooting Common Problems

Problem 1 — Blinding (bars plugging with material)

Symptoms: Bypass volume drops, oversize discharge becomes contaminated with smaller material, deck looks "covered" rather than letting material fall through.

Causes: Wet or sticky feed, clay contamination, undersized bar spacing for the actual fines size, near-size particles wedging between bars.

Fixes: Open the bar spacing (see the grizzly bar spacing guide), switch from straight to stepped or trapezoidal bars, install a spray bar at the feed end if blinding is wet-clay-related, or switch to perforated AR plates for very sticky feeds. See also: how to prevent screen blinding.

Problem 2 — Uneven bar wear (some bars wear much faster than others)

Symptoms: A line of bars on one side of the deck wears noticeably faster, or the feed-end bars wear three times faster than the discharge-end bars.

Causes: Off-center feed loading (the feeder is dumping material onto only part of the deck), feed chute wear forcing material to one side, or normal feed-end vs discharge-end wear gradient.

Fixes: Adjust feed chute liners or feeder discharge to spread load across the full deck width. For inherent feed-end vs discharge-end wear, rotate bars from the discharge end to the feed end at the quarterly window. Use quarter-turn bars to extend life via rotation.

Problem 3 — Bearing overheating

Symptoms: Bearing housing temperature climbs above 85 °C (185 °F) during normal operation, or temperature trends upward week over week.

Causes: Insufficient lubrication, wrong grease type, contaminated grease, bearing wear, misalignment, or excessive load.

Fixes: Verify auto-lube system is delivering grease to the housing. Check grease type against manufacturer spec — never substitute a lower-temperature grease. Drain and refill with fresh grease. If the temperature trend continues upward, plan a bearing replacement at the next opportunity. Never run a bearing to failure — the failure typically destroys the housing and exciter shaft as well.

Problem 4 — Excessive frame vibration / spring-related problems

Symptoms: Visible deflection in the support steel, dust shaking off the surrounding structure, deck orbit becomes elliptical instead of circular, characteristic spring "twang" sound.

Causes: One or more suspension springs has cracked or sagged, spring set has lost preload, support frame bolts have loosened, or eccentric weight imbalance is overloading the springs.

Fixes: Lock out and inspect every spring. Replace any cracked or visibly sagged spring (full set, not individual springs). Re-torque support frame bolts. If eccentric weight imbalance is suspected, open the exciter housings and verify weight positions match the commissioning record.

Problem 5 — Cracked side plates

Symptoms: Visible weld toe cracks, particularly at spring mount brackets or motor mount brackets. Cracks tend to start small and grow over weeks.

Causes: Fatigue from cyclic loading, often accelerated by originally insufficient weld preparation, or by an out-of-spec dynamic load (e.g. running at the wrong speed, oversized eccentric weights, or operating beyond rated tonnage).

Fixes: Drill stop holes at the crack tips immediately to prevent propagation, then schedule a proper weld repair at the next shutdown. Investigate and correct the root cause — operating at higher than rated tonnage, wrong stroke, or out-of-spec amplitude. A repaired side plate will re-crack quickly if the underlying cause is not addressed.

Spare Parts Kit — What to Stock

The right spare parts kit on the shelf prevents most planned-into-unplanned downtime conversions. For a typical ITE Series grizzly running primary scalping at 16 hours/day, stock the following:

Bar Replacement Procedure

Bar replacement is the most frequent major maintenance task on a grizzly. Done well it takes about an hour per deck with two operators. Done poorly it takes a shift and may cause damage to the deck frame.

1. Lockout the machine. Disconnect electrical power, lock and tag, verify zero energy at the motor disconnect.
2. Clear the deck. Remove any tramp material, accumulated fines, or wedged stones from between the bars.
3. Photograph the existing layout. Capture overall and detail shots before removing anything. The photos are invaluable if any question comes up during reinstallation.
4. Loosen fasteners systematically. Work from the discharge end toward the feed end, loosening each bar bolt one full turn before fully removing any. This relieves any built-up stress evenly.
5. Remove old bars. Lift each bar straight up and out. Inspect the deck frame slot for wear, debris, or damage as you go.
6. Clean the frame slots. Wire-brush each slot to remove rust, old grease, or scale. A clean seat is essential for proper bar alignment.
7. Set new bars in position. Lower each new bar into its slot, check that it sits square and flat. Do not force a bar that doesn't drop in cleanly — investigate and correct.
8. Hand-tighten all fasteners first. Snug every bolt before fully torquing any of them. This ensures the bar set finds its natural seated position.
9. Final torque pass. Use a calibrated torque wrench in a cross-pattern (similar to torquing wheel lug nuts on a car). Two passes — first at 60% of final torque, second at 100%.
10. Verify spacing. Walk the deck and measure spacing at three points on each bar. Adjust any bars that are out of tolerance.
11. Re-torque check after first 8 operating hours. Bars settle slightly under load. Schedule a torque-recheck after the first short run.

FAQ

• How often should I lubricate grizzly bearings? If you have an auto-lube system, follow the system's programmed interval — typically every 2 to 4 operating hours for a small grease shot. For manual lubrication, follow the manufacturer-specified interval, usually 100 to 200 operating hours between full purges.
• What grease type should I use? Use only the grease specified by the screen manufacturer. Grizzly exciter bearings run hot and at high speed, and substituting a lower-temperature grease causes premature failure. Typical specs are NLGI 2 or NLGI 3 lithium-complex grease with EP additives rated for 150 °C continuous service.
• Can I weld a cracked bar? No. Manganese steel grizzly bars can be welded but require specialized procedures (low heat input, manganese filler rod, no preheat) that are rarely worth the effort. Replace a cracked bar with a new one.
• How do I know when springs need replacement? Three signs: visible cracks in any coil, a measured loss of free length greater than 5 mm, or a deck orbit that has become elliptical instead of circular. Any one of these justifies a full set replacement.
• What is the typical operating life of a grizzly screen? The frame and structural assembly should last 15–25 years with proper maintenance. Bars wear out and are replaced. Springs and bearings are replaced periodically. The frame itself is the long-term asset, and good maintenance is what protects that investment.
• Should I replace one cracked spring or the whole set? Always the whole set. Springs work as a balanced group; replacing one with a fresh spring next to three older springs creates an imbalanced suspension that accelerates wear on the remaining old springs and causes uneven deck motion.

Need a Maintenance Plan for Your Plant?

Send us your plant's grizzly model, operating hours, and feed conditions — we'll put together a maintenance plan tailored to your duty cycle, with recommended spare parts kit and inspection intervals.

Related guides:

• Grizzly Screen: The Complete Guide — pillar guide
• Grizzly Screen vs Vibrating Screen
• Grizzly Bar Spacing Selection Guide
• Vibrating Screen Maintenance Schedule
• Vibrating Screen Problems & Solutions
• How to Prevent Screen Blinding

Product page:

• GELEN ITE Series Grizzly Vibrating Screens