To those used to seeing QJs shuffling through flat country with minimal effort and barely a hint of colour in the pristine white exhaust, Zhongwei was an eye-opener. The locos were worked hard and black smoke wasn't at all uncommon. QJ 7038 and QJ 7006 produced contrasting exhausts as they dragged a heavy westbound freight around the sinuous curves above Mengjiawan on 10 January 1994.