Simpson Maxidry Tumble dryer (Cloths dryer) How

Tension is typically applied by a non adjusting spring loaded idler pulley.

Here are the steps to get the belt and tension pulley and spring attached properly.
1. Remove the drum from the dryer housing
2. Fit the belt around the drum, secure the belt to the drum (grooved side towards the drum, flat side away from the drum) with small strips of masking tape. Leave a loop of about 10-15 cm's free to fit around the motor. (This was Hurdle #1, it was next to impossible to hold the belt on with one hand and attempt to work out the tension pulley thing at the same time)
3. Place the drum back in to the dryer housing and rotate it so that your belt loop is facing the motor.
4. (Hurdle #2) Attach the tension pulley to the motor assembly bracket. (There should be slots in the bracket for the pulley bracket to insert into. The pulley faces away from the motor, about a 45 degree angle.
5. (Hurdle #3) Feed the belt through (under) the pulley and then over the motor's drive wheel or nub, whatever it's called.
6. (Finaly Hurdle) Attach the spring to the pulley assembly. In the centre of the dryer housing floor, there should be a seam, in the centre of this seam there is a small hole where the other end of the spring attaches too. Stretch and insert the other end of the spring into this hole.
7. Remove the masking tape that's holding the belt down.
8. Re-assemble dryer and your done.

Post your model number here to see diagrams and parts. http://www.searspartsdirect.com/partsdirect/index.action?psid=26129238&sid=PSx20071217x00001a

MOST SERVICE COMPANIES WILL HAVE A BELT, OR RING SIMPSON ON 131350
BEFORE YOU FIT THE BELT MAKE SURE THE CENTRE PULLY IT GOES ON SPINS FREELY- IF ITS TIGHT IT WILL RUIN THE NEW BELT.

After some mild swearing, I made sure that I had the belt around the drum aligned (in the same plane) as closely as I could with the drive pulley and tensioning wheel. I think this was partially achieved by placing the belt as close to that position as possible before lining up the front end of the drum with the cabinet opening, and then turning the drum from the front (through the open door) very slowly clockwise (the direction of its normal rotation) to give the belt "time" to align itself fully with the smaller pulleys. A short prayer and a few minutes later, the machine was humming away with all parts playing their "part" in beautiful harmony - without the dreaded sound of a thin black drive belt cluncking to the floor of the metal cabinet.
Cheers,
Andy B.

Check out applianceaid.com good easy site to follow

loop the belt around the drum.
slide the belt down the drum directly over the motor pulley
loop the belt around the motor pulley
pull the tensioner pulley hard to the end of its travel against its spring
wrap the belt around the tensioner pulley
release the tensioner so the spring pulls it against the belt
rotate the drum by hand to ensure the belt is aligned and does not pull offf the pulleys
reassemble case
dry clothes
its easier than it looks seeing a broken belt in the bottom of the case.

Idler pulley and spring have come off while cleaning dust from inside cabinet a diagram whould be a great help as Im 500kms from nearest service place simpson maxidry 1000p Ray bushed

there is a tensioner pulley as well as the drum and motor
It hooks into a slot, usually on the floor of the case, and has a spring that pulls it against the belt to tension the belt.
Broken belts have been known to knock the tensioner out of place, it should be sitting on the floor of the case as should its spring.
There is usually ony one slot for it to sit in, self evident if you know to look for it
loop the belt around the drum.
slide the belt down the drum directly over the motor pulley
loop the belt around the motor pulley
pull the tensioner pulley hard to the end of its travel against its spring
wrap the belt around the tensioner pulley
release the tensioner so the spring pulls it against the belt
rotate the drum by hand to ensure the belt is aligned and does not pull offf the pulleys
reassemble case
dry clothes
its easier than it looks seeing a broken belt in the bottom of the case.
tensioner may be on the bottom run pushing up, or on the top run pulling down

Looking from rear of dryer,one spring on motor is for tension,therefore put belt around drum(groove to the drum surface).Then rotate the motor firmly clockwise tensioning the spring,take belt from right of drum over tension wheel then put grooves of belt on shaft of motor.Release motor to tension spring,job done !!!!!