Originally Posted by mtmower
What's your reasoning there? I would think any pitch would create less of a seal to the surface causing less vacuum.You don't want that tight of a seal or else the blades lose vacuum, well maybe lose is too strong a word, but they will sure enough have to work a lot harder to gain any vacuum affect. The only reason I could see more pitch creating vacuum would be due to allowing additional air flow to be sucked under the deck at the higher point creating more flow and as a result maybe more vacuum.Exactly right. If this is the case it would seem to make more sense to reverse the deck pitch, making the front of the deck higher than the rear to get the grass to stand earlier within the deck travel/space. Take a good look at your deck, or any commercial Z deck for that matter. They are all designed with the front lip and baffles to be higher than the side and rear skirts to allow the grass to stand more upright before entering the cutting chamber. This would seem to help more in higher ground speeds as well.
Well, I don't have any way to scan them, but several of my Deere manuals show what I am talking about with descriptions and drawings etc. The forwards pitch is so that the blades are only cutting at the front edge of the blade, and it allows the vacuum affect to happen at the rear of the deck as you move forward, which also draws the grass in the direction of travel. The air is being forced out the side chute at high velocity, so drawing it in at the opposite side of the deck (rear) makes perfect sense for maximum air flow to happen. If it drew it all in at the front, it would be immediately redirected out the side chute and you'd have far less, if any, vacuum since the baldes wouldn't have a chance to create any suction anywhere except for the very front of the deck. This is nothing new that I am talking about here. There are lots of recent posts here about this as well.