Despatch S Type - Manual (Page 95)

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With oven cold, check to see that the roller rests are adjusted properly and tightened down,
preventing the roller rests from moving. The door lowers down on the roller rests and,
depending on how fast the door is moving, puts a lot of force on the roller rests.
Permanently mark or pin roller rests in place after final adjustment for future
checking/inspection. If the door seems to be traveling fast and coming down hard on the
rests, the cylinder flow controls should be adjusted to slow down the door rate of decent.
Roller rests must be positioned evenly so contact is made at the same time. Door should
come down and cam in evenly (lift chain or roller rest adjustment may be required) so as to
meet the oven front and floor with very light pressure on the floor seal. At the same time, the
door should cam in as the door rollers roll down the slope of the roller rests attached to the
door hoist columns, sealing the door around the perimeter of the door to the front of the
oven. Cycle door 6 to 8 times to make sure that the door works consistently without hanging
up on roller rests or possibly between the rests and the inside vertical roller guide angle,
which could possibly hold back the door roller from rolling down the roller rest and thus
preventing the sealing of the door. Check to make sure that the seal holders are not
preventing the door from caming in and sealing properly on both the inside and outside
seals. In other words, if door touches the floor before the door cams in freely, the lower
sides of the doors will not move in to provide proper sealing. Refer to door adjustment
procedure for additional guidance.
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With the oven cold, check to see that the door is balanced in a free hanging position (from
the hoist chains), ensuring that the bottom of the door is not kicking out away from the oven
front when the door reaches the closed position (where the bottom of the door meets the
floor). If the door is not balanced, chain and sprocket adjustments may be required. If
required, the chains can be shifted at the top of the door. If the chains are too tight, this may
prevent the door from fully resting on and rolling down the roller rests, preventing a tight
seal against the front of the oven.
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With the oven cold, from inside the oven check the internal oven front breaker seal (found
on 850
_
F designs) for complete sealing against the door perimeter. Cycle door 6 to 8 times.
Since seals are new, they will compress some and may need readjustment, especially the
inside front breaker seal. Double check the outside door seals (all designs) in the same
fashion. Any adjustment on either seal requires that you recheck both seals again for proper
sealing.
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Oven pressure - how positive is the oven? Excessive positive pressure could result in
warpage of the door and/or oven front. This problem would normally show up at the top of
the door where the pressure and heat have more impact due to the free span of the wide
opening and where thermo expansion would be most noticeable. Generally, if a sealing
problem exists in the lower areas at the sides of the door, the problem is due to the door not
sealing or barely sealing from the start, and the problem just worsens as you increase oven
temperature or pressure. Once again, the roller rests may not be sloped enough or the hoist
chains may be too tight, thus preventing the door from rolling down into the front of the oven
for a tight seal.
If you have any further questions, or you do not understand the theory of the door design or the
explanations above, please do not hesitate to give us a call. Feel free to contact us through our
1-800 number found in the manual.