CHRISTIE PACIFIC CASE HISTORY: MASPORT VACUUM PUMP REBUILD

Tuesday

MASPORT VACUUM PUMP REBUILD

We repaired this MASPORT H15W vacuum pump. It was part of a Non-destructive digging plant.

As we had no idea of the condition of this vacuum pump, it was removed from the truck and stripped down.

These are very simple machines in theory, but in practice they require a lot more attention that most imagine.

After a good hot wash and chemical clean we could get to work.

Clearances are of the utmost importance, and any deviation can cause untold problems.

So out came the measuring tools and the results were compared with the manufactures specs.

Here is a handy check-list to guide you.

The belt driven Masport vacuum pump.

It soon became evident that this vacuum pump was in serious trouble.

As can be seen in the photos below, the housing had worn badly.

The corrugated finish or surface inside the housing was affecting the performance of this vacuum pump.

This was most probably the result of running the pump at to-low a speed, causing the vanes to chatter.

This chatter in turn wears out the housing, giving it a wave like finish.

Corrugated wear pattern

This housing still with-in spec, so she was machined and honed, ready for a new life.

The end plates or covers were also inspected for wear.

Contamination is also a big enemy to these vacuum pumps.

Poorly filtered air carries dirt and grit that gets lodged between the rotor and end plates.

Notice the vane's, 4 of them, they to are prone to a lot of wear and tear.
They have to be replaced or machined before assembling the pump again.

These end covers are still fine.

No signs of wear, no groves or scratches, no rough patches that would make a poor vacuum seal.

The rotor and shaft were also given a good once over.

The shaft was checked for run-out.

The rotor also checked for run-out, but at the same time the clearance between the vane and the rotor grove were checked.

Everything was in spec; only the bearings were in poor condition, so they were replaced.

Critical to performance is the end float and clearance between the rotor and end plates.
After much set-up, we were happy, and assembly began.

Diagram of all the parts.

After assembly the pump was ready to be fitted to the new mounting plate and stand.

This we fabricated from scratch as the last one was destroyed.

New pillar bearings were also fitted and everything was lined up.

Another great killer to these pumps is the lack of lubrication.
Fitted with an oil dosing pump that is pulsed by the rotor shaft, the correct grade and flow of lubricant is vital.
No oil means the vane build up excessive friction, that causes heat and in turn that bring home failure.

Here the pump and stand is in the process of being fitted to the Non-Destructive Digging plant \ truck.

Nathan , my favorite son, fitting the vacuum pump and stand to the truck.

This oil tank was fitted to provide lubricant for the vacuum pump.
Sight line or glass was important, not good idea to run out off oil in the middle of a job!

All plumbed up! Notice the sight glass on the coolant tank, the big shiny ally tank on the right.
An electric Dave y pump circulates the coolant between the tank and the Masport vacuum pump.