Belt Tensioner 21549016

This is an Automatic Belt Tensioner assembly used extensively across Volvo’s heavy-duty engine platforms, including those in trucks, articulated haulers, excavators, and wheel loaders.

Product Specifications

Average Weight: ~ 1.7 kg

Supersession: 20924200 > 20700787 > 20515543 > 21549016

Engine Compatibility: Commonly paired with D11, D13, and D16 engines

Machine Compatibility: T450D ; A25F ; A30F ; A35F ; A35F FS ; A40F ; A40F FS ; EC480D ; EC380D ; L150G ; L180G ; L220G ; L180G HL ; L250G ; PL4809D ; EC480DHR ; EC380DHR ; EC380E ; L150H ; L180H ; L180H HL ; L220H ; L250H ; A25F/G ; A30F/G ; A35F/G ; A35F/G FS ; EC480E ; EC350E ; EC380EHR ; EC480EHR ; PL4809E ; A25G ; A30G ; A35G ; A40G ; L150H ; L180H ; L180H HL ; L220H ; L260H ; EC530E ; EC550E ; EC380 ; EC480 ; EC500 ; EC400E LSCN4 ; EC500E LSCN4 ; L200H HL ; EC370F ; EC400F ; EC500F ; EC650E ; A25J ; A30J ; A35J ; A40J ; L150K ; L180K ; L220K ; L260K ; L200K HL ; EC500FHR ; EC400FHR ; LC450K ; A35D ; A40D ; FH/FM/FMX trucks

SL: 3B

Key Information

This component is vital for the engine's accessory drive system. It uses an internal spring mechanism to apply constant, calibrated pressure to the serpentine belt. This ensures the belt remains tight enough to drive critical components—like the alternator, water pump, and A/C compressor—without slipping, while simultaneously compensating for the natural stretching of the belt over time.

These units are typically constructed from high-strength steel and aluminum alloys. They are designed to withstand the high-vibration and high-heat environment of a heavy-duty diesel engine bay, ensuring long-term stability and reducing the risk of unexpected roadside breakdowns.