Wheelhorse charger 10

I just picked up a 1969 charger 10 and I'm having trouble with the drive belt for the automatic trans. I replaced the idler pulley for the tensioner which was bad and put on a new belt. The belt stays on sometimes but quite often will jump off the pulley especially when putting the parking brake on or off.

When belt jumps off trans pulley-do you have belt cover installed & is belt pn 7478?

I have the correct belt and It does seem to be happening with the cover off

Install belt cover & see if that cures problem,the charger/raider series belt clutch were designed to be operated with belt cover installed,the lip on bottom of cover & tab on idler pulley bracket or inside of belt cover(I don't remember which as it's been 3 yrs since I've had my cover off)dampen/limit the flapping of upper/lower loop of belt when belt engaged or belt being engaged/disengaged.

Before installing belt cover goto link below & look at spring connection,confirm that spring on your tractor not disconnected,broken or missing,this spring maintains tension on idler pulley assembly to keep belt tight when clutch engaged(hand operated belt drive clutch,not foot operated clutch).

IF you still have problem with cover on,remove cover,drive belt & spring,check all cross shafts associated with clutch for binding/stiffness,also check bushings on same,pivot pins/pivot pin holes for wear/slop.The clutching mech shown in pic was on a charger 12 I scraped several yrs ago,as you can see by wear on lower spring arm,the clutching mech was worn & needed a complete rebuild/replacement & hydro pump/motor were weak due to wear & needed rebuild/replacement,most/all parts needed for rebuild are nla from sundstrand or toro.
spring

Thanks for that information Joe. The lower arm on mine looks very similar. I wasnt sure if it was susposed to be that way. Is the belt susposed to stop turning completely when the parking brake is on?

With belt cover INSTALLED & engage lever in UP position belt should NOT move & be free of eng pulley,if you look inside of belt cover you will either have a short rail welded to inside of lower part of cover or a lip on bottom of cover.

In operation when engage lever in up position the lower loop of belt drops onto rail/lip,this supports lower loop of belt,all slack in belt is now trasfered to top loop,this causes top loop of belt to move forward & disengage eng pulley,without cover installed top/bottom loop of belt keep dropping due to their own weight keeping belt engaged with eng pulley.The actual brake/parking brake is an internal hyd function of transaxle & regulated by the position of directional control valve(for/rev) or if drive belt disengaged thru a system of relief/check valves in pump manifold,this action now traps hyd fluid in pump & hydro motor locking rear wheel,this is why you have a freewheel/tow valve on pump manifold,opening this valve 1/4-1/2 turn releases trapped hyd fluid in pump/hyd motor & allowing rear wheels to turn so you can push tractor by hand or tow.

i have installed the belt cover but the drive belt still turns when the parking brake lever is on. It appears the linkage is fully extended to get the idler as far away from the belt as possible but the belt is still engaged. I double checked the belt as well and its 84" which seems correct. Any ideas?

I checked my charger 12 tractors & also checked at partstree,looking at assembly drawings/parts list looking at listings for charger 9-12 & my tractors all have a full length guide rail welded to inside of cover,check that same not missing from cover,without removing cover,from left side of tractor(eng flywheel side)look around battery or between battery/eng confirm rail there,also with parking brake/clutch handle(depending on your point of view)in UP position confirm belt laying on TOP of guide rail and that belt NOT under rail(easy to do,been there done it)if belt under rail this can cause problem you have.

If rail/belt routeing not the problem,remove cover & check that eng/trans pulleys not loose or out of alignment,if pulleys lined up I would suspect previous owner may have changed/replaced eng pulley or linkage parts for idler pulley worn allowing pulley to stay in contact with belt.