Small Engines (Lawn Mowers, etc.): Riding Mower Cutting Deck, pto belt, troybuilt

Question
I have a Troybuilt #188392, 18hp rider w/42" blades.  Lately when I engage the cutting deck the engine continues to run at full speed, but when I lower the cutting deck, the rpms go way down. I have changed both the lower deck belt and the PTO belt, but they didn't make a difference.

Answer
 Hello Robin:

 Check the Belt Routing with the Deck Down. Are the Belts Rubbing on Anything. If Yes, then Route the Belt Properly. If No, then Remove the Belt from the Cutter Deck Blade Pulleys and then Engage the Blades(Do Not Start the Engine). This Releases the Blade Brakes. Now Turn the Pulleys by Hand. Do they Turn Free. No Binding or Grinding Noise. If the Bearings in 1 or Both of the Mandrels/Quills is Bad the Engine will Act as you Described. You can View a Breakdown/IPL of the Mower at this Addy http://www.buymtdonline.com/webapp/wcs/stores/servlet/Home_BuyMTDOnline_10101_19... and Scroll to the Bottom of the Page and Click on the Troy-Bilt Logo. Then Select Use Our Detailed Parts Finder. Then Enter the Model Number and Click Search. Hope this Helps. I am here if you Require more Assistance. Let me know what Happens, Please. Thanks.

 Good Luck

 Respectfully

 John