A landscaping contractor reported that a CASE SV280 skid-steer loader developed a jerky, pulsing drive behavior under load. When the operator pushed into a pile with the bucket, the machine would surge forward, momentarily lose drive on the right side, then surge again. Traveling in a straight line on pavement, the loader pulled slightly to the left, and a rhythmic "clunk" was audible from the right-side chain case.
The technician first recognized the symptoms of a chain-drive fault. Skid-steer loaders like the SV280 transmit power from the hydraulic drive motors to the wheels through heavy roller chains and drive sprockets enclosed in the side chain cases. Proper chain tension is critical: when slack exceeds specification, the chain can skip over sprocket teeth under shock load - producing the surge-and-release behavior the operator described. Sprocket alignment is equally critical; a misaligned sprocket accelerates chain wear and produces uneven tooth engagement.
To inspect the chain, the technician removed the right-side tire and rim assembly, then took off the center inspection cover to access the chain case. Inside, he measured chain slack at mid-span: 35 millimeters of sag (spec maximum is roughly 15 millimeters), well beyond the adjustment limit. He then rotated the drive sprocket by hand and observed the chain engagement - several sprocket teeth on the right drive sprocket were visibly hooked and worn to a shark-fin profile, indicating the chain had been running loose long enough to erode the tooth flanks. The chain's rollers and side plates also showed elongation beyond 3 percent of original pitch (the service limit is typically 2 percent), confirming the chain itself was beyond adjustment and required replacement rather than re-tensioning.
The root cause was traced to missed preventive maintenance. Skid-steer drive chains should be checked for slack at every engine oil change interval, and the chain cases should be topped up with the specified gear oil - which both lubricates the chain and cushions shock loads. The SV280's chain case oil was found nearly empty, likely from a slow case gasket leak that had gone unnoticed; the dry chain had worn rapidly, elongating and eating into the sprocket teeth.
The repair involved replacing the right-side drive chain with a new unit, replacing the worn right drive sprocket (the hooked tooth profile would have destroyed a new chain within weeks), and replacing the left-side chain and sprocket proactively since both were the same age. The chain case gasket was replaced to stop the oil leak, the case was filled with the specified gear oil to the correct level, and the chain tension was set to specification - cycling the drive forward and reverse, shutting down, and rechecking slack to account for chain seating. After reassembly, the loader pushed into a full bucket load without surging, tracked straight on pavement, and the rhythmic clunking disappeared. The technician added chain-case oil level and chain slack to the machine's 250-hour service checklist to prevent recurrence.
