Scalping Screener Inspection Guide: What to Check Before You Buy
A used scalping screener can be one of the best purchases you make. It can also be one of the most expensive mistakes. The difference comes down to what you checked before you signed anything.
This guide walks through every system to inspect, in order. Bring it with you. Work through it item by item. A visual walk-around cannot tell you everything a scalper hides. Worn screen media, a failing exciter, or a crack starting in the screen box frame all take a hands-on check to catch.
If you have not read our used scalping screener buying guide yet, start there. This article goes deeper on the inspection step.
Before Your Scalping Screener Inspection
A few ground rules.
Ground rules
- Wear appropriate PPE and follow standard jobsite safety practices. Heavy equipment inspection carries real physical risk, in addition to the specific hazards called out below.
- Inspect cold first. A machine that has run all day hides leaks and wear. Arrive before the seller starts it up, if you can.
- Bring someone with you. Operational checks need one person at the controls and one person watching the screen box and conveyors.
- Never climb onto the screen box or walk on top of the machine without fall protection and a secured surface. Falls from height are one of the more common serious injuries around screening and processing equipment. Use a harness or a certified ladder or platform, never step onto material stockpiles or screen decks to gain height, and confirm the surface you are standing on can actually hold your weight before you put weight on it.
- Never reach near a moving conveyor, feed hopper, or discharge point while the machine is running. MSHA’s belt conveyor safety alert (opens in a new tab) documents eight conveyor-related mining fatalities industry-wide since 2017, most from miners working near a moving conveyor or servicing one that was not blocked against motion. Lock out, tag out, and block the machine against motion before you reach into or near any conveyor, feed hopper, or discharge point, even just to clear material or check a roller.
- Ask to see the machine run under load before you commit to anything else. Screen media condition and vibration problems often only show up while the machine is working.
If the seller will not let you run the machine, or will not let you get a proper look at the screen box with fall protection, walk away. No exceptions.
System 1: Screen Media
Start here. The screen media is what actually sorts the material, and it takes the most direct wear of any part on the machine.
Machine off
- Check both decks for tears in the mesh, cracked or deformed punch plate holes, and gaps between panels where material can bridge through.
- Confirm every panel sits tight in its frame. A loose panel vibrates more than it should and wears out faster than the rest of the deck.
- Look for hardened material packed between panels or built up in the frame. Buildup left to harden between jobs speeds up wear and can throw off the screen’s balance.
- Ask when the media was last replaced on each deck, and what it was replaced with. Punch plate and mesh wear at different rates.
Machine running
- Feed a test load and watch both discharge conveyors. Oversized material showing up in the fines stream, or product coming off the wrong conveyor, points to a hole or gap you missed on the walk-around.
- Watch the feed spread evenly across the full width of the deck. Material piling up on one side wears that section faster and can mean the deck is out of level.
What it costs if you miss it
A full punch plate deck replacement can run several thousand dollars per deck. Mesh costs less per panel but wears out faster and needs replacing more often. Either way, worn media costs you in bad product grading long before it costs you in parts.
System 2: Vibrating Mechanism and Springs
The exciter drives the entire screen box. Everything else on the machine only works if this system is right.
Machine off
- Check each isolation spring for even compression, corner to corner. A spring that sits lower or feels softer than the others is on its way out. Springs typically run 3,000 to 5,000 hours before they need replacing, and they should always be replaced as a full set, not one at a time.
- Look at the exciter or gearbox housing for oil weeping, and check the mounting bolts for looseness.
- Check the drive belts or coupling between the motor and the exciter for wear or cracking.
Machine running
- Run the screen empty first. Listen for grinding, knocking, or a steady thump. Any of these can mean a worn bearing inside the exciter.
- Watch the stroke at all four corners of the screen box. Quarry Magazine’s guide to checking screen amplitude (opens in a new tab) explains how a mismatched spring, an uneven feed, or a failing exciter bearing all show up as an uneven stroke between corners. If you have access to a magnetic stroke card, use it. If not, watch for a screen box that visibly shakes unevenly side to side.
What it costs if you miss it
A full spring set typically costs several hundred to a couple thousand dollars, depending on the machine. An exciter or gearbox rebuild costs several times that. Running on a bad spring stresses the exciter bearing directly, so a cheap fix ignored today usually turns into the expensive fix later.
System 3: Undercarriage
What you check here depends on how the machine travels.
Tracked units
- Check track tension, and look for cracking, chunking, or uneven wear on rubber tracks.
- Inspect rollers, idlers, and sprockets for wear and play.
- Cycle the track drive forward and reverse if the machine can self-propel. Listen for grinding in the final drives.
Wheeled or skid-mounted units
- Check axle bearings, brakes, and tire condition or, on a skid frame, the skid rails and mounting points for cracking.
What it costs if you miss it
Rubber track replacement typically runs a couple thousand dollars per side. Roller and sprocket wear adds up over time but costs less than a full track change if you catch it early. It is a smaller bill than a screen box repair, but it is also one of the easier systems to skip on a quick walk-around.
System 4: Hydraulic System
The hydraulic system folds the conveyors and raises the feed hopper for transport on most scalping screeners.
Machine off
- Look for oil on the ground under the hydraulic pump, valve bank, and every hose along the frame.
- Check the fluid level and condition. Clean fluid is amber to light brown. Dark, milky, or burnt fluid is a problem.
- Check the cylinders that fold the side conveyors and raise the hopper for rod scoring or leaking seals.
Machine running
- Cycle the folding conveyors and the feed hopper through their full range. Listen for whining or knocking under load.
- Watch every hose and fitting again once the system is pressurized. New leaks often only show up under real pressure.
What it costs if you miss it
Hydraulic pump replacement runs several thousand dollars in parts alone. Cylinder or seal replacement runs a few hundred to over a thousand dollars per unit. A hydraulic failure does not just cost money. It can leave the machine stuck in transport configuration on site.
System 5: Engine
Machine off
- Pull the dipstick. Milky or burnt oil is a problem.
- Check coolant condition and look for leaks around hoses and the radiator.
- Check the hour meter reading against the machine’s service records.
Machine running
- Start the engine cold if you can. Listen for knocking, and watch the exhaust for excess smoke.
- Let it idle, then run it under load. It should hold a steady idle and respond cleanly when the screen engages.
What it costs if you miss it
Engine repair costs run anywhere from a few hundred dollars for minor issues to several thousand for major work. An engine problem on a scalper is often the cheapest system to check and one of the most expensive to ignore.
System 6: Conveyors and Structure
Machine off
- Check conveyor belt condition, tracking, and roller wear on the feed and discharge conveyors.
- Walk the full length of the chassis and screen box frame. Look closely for cracked welds, especially around the spring mounts and the points where the screen box attaches to the frame.
- Check that the frame has not been repaired with a weld patch that was never properly reinforced.
Machine running
- Watch the conveyors track straight and feed at a steady rate, without slipping or wandering to one side.
What it costs if you miss it
Belt and roller replacement runs a few hundred to a couple thousand dollars. A cracked frame or screen box repair can run into the thousands and, depending on where the crack is, may not be a repair worth making at all. See Red Flags below.
When to Bring a Professional
If you are not comfortable checking the exciter, hydraulics, or structural welds yourself, hire a third-party inspector or a technician certified through the manufacturer. This is also worth doing if the machine’s price justifies it. Above $200,000, a professional inspection is worth the cost. The fee is almost always less than the cost of one exciter rebuild or a frame repair you did not see coming.
Red Flags That Should Stop the Deal
Some findings are reasons to walk away unless the price reflects the problem clearly:
Walk away unless the price reflects it
- Cracked welds on the screen box frame or chassis, especially around the spring mounts.
- A collapsed, mismatched, or visibly uneven isolation spring.
- An uneven or excessive stroke at the screen box corners under load.
- Hardened material packed into the screen box that the seller has not cleared out.
- Oversized material coming through in the fines stream during a test run.
- A seller who will not run the machine under load or will not let you get a proper, safe look at the screen box.
Once you are satisfied with what you found, you know what to look for. PayDirt HQ lists scalping screeners for sale, with financing options available (opens in a new tab) through Equify Financial.
If you still need it, our used scalping screener buying guide covers sizing, machine history, sourcing, and financing in more depth.
Frequently Asked Questions
How long does a proper scalping screener inspection take?
Plan for one to two hours on a standard machine. It takes longer if you also want to run a full load test through both decks. Anyone who offers to do it in 15 minutes is skipping the parts that matter most.
Can I inspect a scalping screener myself, or do I need a specialist?
You can do the visual and operational checks yourself. Checking the exciter, hydraulics, and structural welds goes faster with hands-on experience. Above $200,000, a professional inspector or a manufacturer-certified technician is worth the cost.
How do I know if the screen media needs replacing?
Check it weekly if you own the machine, and closely at purchase. Look for cracked or deformed punch plate holes, torn or sagging mesh, and gaps between panels. If the shape of the openings has visibly changed, or product quality has dropped, it is time to replace it.
Does a high hour count automatically mean the machine is a bad buy?
No. Maintenance and screen media replacement history matter more than hours alone. A well-documented machine with regular service can beat a low-hour machine with no records. You cannot verify what a machine with gaps in its history has actually been doing.
What if the seller will not let me run the machine under load?
That is a red flag on its own. A seller confident in the machine's condition lets you see it work, media, exciter, and all, before you commit.
This guide is general information for equipment buyers, not professional advice. Cost and value ranges are editorial estimates that vary by region, condition, configuration and market. Verify against current quotes and a qualified inspection before making a purchase decision.
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