List of free sample libraries

[sayan]

Trailer SFX and Trailer Percs (Wav, Kontakt and Kontakt Player)

Ferrum is top-notch freebie for Trailer percs and is compatible with the free Kontakt Player. Their download manager gets flagged as malicious by Windows for some reason but you can request a direct download link from them.

Rest all are trailer transition SFX like risers, downers and pulses.