CEMA Classes, Decoded

Idlers carry the belt and the load; when they seize or wear out, you get mistracking, spillage, drag, and belt damage. CEMA classes set the duty level, and the number is the roll diameter in inches:

Class	Duty	Roll Diameters	Belt Widths
CEMA B	Light duty	4”–5”	18”–48”
CEMA C	Medium duty	4”–6”	18”–60”
CEMA D	Medium-heavy duty	5”–6”	24”–72”
CEMA E+	Heavy duty	6”–7”	36”–96”

Standard troughing angles are 20°, 35°, and 45°, and every position has its style: equal and offset troughing, impact, feeder/picking, flat carrying, returns (steel, rubber disc, V-return), self-aligning trainers for wandering belts, and scale-quality rolls for belt scales.

Douglas Idlers — Sealed for Life, Made in the USA

Douglas builds its idlers in Pell City, Alabama with sealed-for-life precision ball bearings (no greasing, ever), machined shouldered shafts, and rigid self-cleaning welded frames. The current-generation PSV roll adds a triple-labyrinth hybrid seal system — stone guard, external wiper, labyrinth, and internal seal — to lock out dust, dirt, and water, the contamination that kills most bearings. Dozens of styles across CEMA B, C, and D cover every position on the conveyor, with emergency lead times available when a line is down.

Enduride Composite & Polymer Rollers

Enduride’s composite roller technology changes the replacement math: rolls up to 50% lighter than steel with the same load capacity, corrosion-proof, and up to 12 decibels quieter — easier on the crew doing the swap and on the neighbors. A patented triple-labyrinth seal targets the three big bearing killers (contamination, vibration, shaft deflection) for up to 3× life expectancy, rated from −40° service. Their HDPE/UHMW-covered rolls put a half-inch polymer wear layer over steel for up to 6× the life of a conventional roller — with a built-in wear indicator: when steel shows, it’s time to change. Ask us about the Enduride One-Man Idler line and scale-quality precision rolls, and about composite options up to CEMA F.

Protect the Load Zone

Most belt damage starts where material lands. Impact idlers with rubber cushion discs — or full impact beds — absorb the energy of falling material, protecting the belt cover and the bearings beneath it; Enduride credits impact beds with extending belt life up to 300%. Pair them with proper skirting and sealing and the load zone stops being your maintenance headache.

Conveyor Safety Netting

Steel guards protect people — and then slow down every inspection. Enduride’s tensioned safety nets guard pinch points and catch falling rollers (including a return basket made specifically for return rolls), while the see-through mesh lets crews monitor components without removing anything. Sections run up to 18 feet long and 36”–79” high, open with a simple tool for maintenance, retrofit most installations, and are engineered to CSA Z432 and ISO 13857 guarding standards with MSHA-accepted fire-resistant material (IC336/01).

When to Replace an Idler

• Seized or flat-spotted rolls — they grind the belt cover, add drag, and can become a heat and fire risk
• Squealing or grinding bearings
• Belt mistracking or spillage that keeps coming back
• Material buildup on rolls pushing the belt off center

© 2026 The ACT Group (Applied Conveyor Technology). All rights reserved.