Tweco Thermal Arc TA 500 - Manual (Page 38)

Service 4-4 Manual No 0-0470
The pump is pre-greased at the factory and should only re-
quire lubrication every two years. To lubricate, remove screws
from the two grease fittings on top of the pump and apply
grease supplied with the HE 200 unit.
CAUTION
Do not over-lubricate the pump; it will cause
pump failure.
The fan belt may become loose due to usage. The belt
tension should be such that moderate finger pressure
(about mid-distance from pulley to pulley) gives about
1/4 inch (6 mm) deflection. The belt tension may be
adjusted by changing the width of the gap on the large
adjustable pulley. Using a 5/32 hex key wrench loosen
the two set screws 180 degrees apart on side of pulley.
Remove key and rotate by half turns until desired gap
is obtained. Replace the square key and tighten set
screws again.
4.4 Gas Pressure Regulators
The Thermal Arc gas pressure regulators provide a
means of conveniently selecting and maintaining the
required working pressures of the gases. The regula-
tor will hold this pressure constant. Inlet pressure is
reduced in one step to the working pressure by means
of a pressure balanced poppet valve controlled by a
spring loaded piston in a low pressure chamber. A large
adjusting spring knob (6, Figure 4-C) provides for ad-
justing spring pressure against its piston. A sintered
stainless steel filter, in the inlet connector (1), prevents
dirt from entering the regulator mechanism.
No regular maintenance of the gas pressure regulators
is required, except an occasional lubrication of the ad-
justing screw thread and on its end, where it contacts
the adjusting spring. Lubricant is available from Ther-
mal Dynamics for this purpose (Catalog No. 9-2781).
Replacement parts in the regulator include the pres-
sure gauges, the O-ring seals on the piston and above
the poppet valve, and the poppet valve. (See Assem-
bly Parts List Fig. 5-12 for replacement parts).
1
6
5
2 4 3
A-01894
1. Inlet connection
2. Inlet pressure gage
3. Safety valve
4. Working pressure gage
5. Hose connection
6. Adjusting knob
Figure 4-C Components of Gas Pressure
Regulator
CAUTION
Do not attempt to remove the sintered metal fil-
ter in the inlet connection. This is not a service-
able item.