15 yards? We under rate ours from 20-23m3 to 16m3 which is just under 21yd3. You'd have to have some pretty big voids to lose 6yd3s a load.
What are the other trucks you are using? If you have Komatsu trucks take them out of economy mode for uphill hauling!
According to the Rimpull-Speed-Gradeability information both the 740 and HM400 are evenly matched, the only thing I can think of is that he's either getting a better run at the hill, using his tranny hold to prevent the upshift then immediate downshift again you get when climbing ramps sometimes, or he's picking up time in other places. Not putting the park brake on at the hoe saves a couple seconds when leaving, same thing for dumping. Using the two foot method when dumping saves time too (back up, drop to nuetral, left foot to hit brake, right on accelerator for hydraulic pressure at the hoist.
Is he passing you on the hill or just passing you a lot in general? Or is he even passing you (some truck jockeys like to claim their load counter is higher than everyones as they just add a couple loads to their actual count at the end of the day)?
Not going to the can every 15 minutes can add a lot of extra loads at the end of the day, same thing for being the first one out in the morning, after break/lunch and going for the last load at the end of the day.
