What brands of positive displacement blowers do you repair?

We commonly see Roots and Howden Roots, Gardner Denver and Sutorbilt, Tuthill, Aerzen and Kaeser blowers, and we rebuild other brands and older unsupported units as well. We are an independent shop, not an authorized service center for any blower manufacturer.

Why did my blower's lobes start hitting each other?

Lobe contact almost always follows a bearing or timing gear problem that lets the rotors drift out of position, or overheating from a restricted discharge that makes the rotors grow into each other. The contact is the result, not the cause, so the rebuild has to find and fix what let the clearance close.

Can you rebuild a blower if the housing is scored?

Usually, yes. Housings and end plates are bored and faced back to true on our mills, and clearances are restored by machining or by repairing or replacing the rotors. We will tell you if the damage is too deep for the housing to be saved.

Do you balance the rotors during a rebuild?

Yes. Rotors are balanced during every rebuild and after any lobe repair. Imbalance is the most common reason a freshly rebuilt blower loses its bearings early.

Do you replace timing gears and reset the timing?

Yes. Timing gears are inspected for backlash and tooth wear, replaced when out of limit, and the rotors are retimed at assembly. Every clearance is double-checked after timing.

How long does a PD blower rebuild take?

It depends on the frame size, the damage found at teardown, and parts availability. Call with the make and model and we can give you a realistic estimate.

PD Blower Repair

Repair & Service

Positive Displacement (PD) Blower Repair & Rebuild

Precise Mechanical repairs and rebuilds positive displacement blowers, including Roots-type and rotary lobe blowers, at our machine shop in Houston, Texas. A rebuild covers teardown and failure analysis, lobe and shaft repair, bearing and timing gear replacement, seal replacement, housing machining, rotor balancing, and reassembly to original clearances. We commonly see Roots and Howden Roots, Gardner Denver and Sutorbilt, Tuthill, Aerzen and Kaeser blowers, and we ship rebuilt blowers nationwide.

What a PD Blower Does and Why It Fails

A positive displacement blower moves a fixed volume of air or gas with each revolution using two (or three) lobed rotors turning in opposite directions inside a close-fitting housing. The rotors never touch each other or the housing; a pair of timing gears keeps them synchronized with a few thousandths of an inch of clearance. That clearance is the whole machine. When it opens up, capacity drops. When it closes, the lobes contact and the blower destroys itself in seconds.

Nearly every PD blower failure traces back to one of five things: bearing wear that lets the rotors drift, timing gear wear that lets them lose synchronization, thermal growth from a restricted discharge, contamination through a failed seal or dirty inlet, or an imbalance that hammers the bearings until they give out.

Symptoms and Likely Causes

Symptom	Likely cause	What we typically find at teardown
Lobe contact (metallic knock, sudden seizure, metal in the discharge)	Bearing wear or failure letting rotor float; timing gear backlash worn past limit; thermal growth from overheating	Scored lobes and housing, bearings with spalled races, gears with worn or chipped teeth
Bearing or gear failure	Lubrication breakdown, wrong oil level, contamination, overload from belt tension or misalignment	Discolored races, oil sludge, worn gear faces, damaged shaft journals
Timing gear wear	High hours, lube starvation, shock loading from surge or slugging	Excess backlash, pitted tooth flanks, rotor-to-rotor clearance out of spec
Seal leaks (oil at the vent, oil in the air stream, process gas at the shaft)	Worn lip or mechanical seals, scored shaft under the seal, plugged vent	Grooved shaft, hardened or torn seals, oil-fouled rotor chamber
Overheating from restricted discharge	Closed valve, plugged silencer or filter, downstream fouling, relief valve not opening	Blued rotors, heat-checked housing, rotor tips rubbed from thermal growth
Loss of capacity or pressure	Worn rotor-to-housing and rotor-to-end-plate clearances; erosion from abrasive process gas	Clearances well beyond OEM limits, worn end plates
Vibration	Rotor imbalance from material buildup or erosion, bent shaft, failed bearing, loose base or coupling	Rotor out of balance, shaft runout, bearing housings worn

Brands we commonly see

We are an independent shop and are not an authorized service center for any blower manufacturer. The brands that come through our door most often are:

Brand	Typical types
Roots / Howden Roots	Bi-lobe and tri-lobe rotary blowers, small frames through large process blowers
Gardner Denver / Sutorbilt	Rotary lobe blowers and vacuum boosters
Tuthill	Rotary lobe blowers and vacuum boosters
Aerzen	Rotary lobe blowers and packaged blower units
Kaeser	Rotary lobe blowers and packaged blower units

If your blower is another brand, or an older unit whose manufacturer no longer supports it, we can still rebuild it. Our shop reverse engineers obsolete parts as a normal part of the work.

Shop capabilities

How We Rebuild a PD Blower

The rebuild follows the same seven-step process we use on liquid ring vacuum pumps. Read the full 7-step repair process

Tear down and inspection. The blower is completely disassembled. We measure every clearance before cleaning so we can see what the blower was actually running at, then identify the cause of failure.
Materials inspection. Rotors, shafts, housing, end plates, gears and bearings are inspected and measured. All replacement materials and remanufactured parts meet current OEM specifications.
Remanufacturing. Housings and end plates are bored and faced to restore true bores and square end faces. Scored shafts are sleeved or remade. Damaged lobes are repaired or the rotor is replaced. Parts that are no longer available are reverse engineered and machined in-house.
Tolerances. Rotor-to-rotor, rotor-to-housing and rotor-to-end-plate clearances are set to original OEM tolerances. Gear backlash is checked and set.
Assembly. New bearings, seals and gaskets are installed and the rotors are timed. Every clearance is double-checked with feeler gauges after timing, because a blower that is right on the bench and wrong after gear installation will contact on startup.
Painting and coating. The blower is primed and painted per customer specification.
Final inspection. The assembled blower is turned by hand and inspected before crating.

Balancing

Rotor imbalance is the quiet killer of PD blower bearings. Buildup on the lobes, uneven erosion, and repairs that add or remove material all shift the balance. We balance rotors during every rebuild and after any lobe repair, so the blower goes back into service without the vibration that took out the last set of bearings.

Larger Blowers and Packaged Units

Because our shop is built around large liquid ring vacuum pumps, big blowers are not a problem. Housings go on the same vertical boring mills and horizontal mill, and long rotor shafts run in lathes up to 240 inches between centers. If your blower is part of a skid, we can also replace the motor, belt drive or coupling, and rebuild the base as part of the job. Packaged units →

Frequently Asked Questions:

What brands of positive displacement blowers do you repair?

We commonly see Roots and Howden Roots, Gardner Denver and Sutorbilt, Tuthill, Aerzen and Kaeser blowers, and we rebuild other brands and older unsupported units as well. We are an independent shop, not an authorized service center for any blower manufacturer.

Why did my blower's lobes start hitting each other?

Lobe contact almost always follows a bearing or timing gear problem that lets the rotors drift out of position, or overheating from a restricted discharge that makes the rotors grow into each other. The contact is the result, not the cause, so the rebuild has to find and fix what let the clearance close.

Can you rebuild a blower if the housing is scored?

Usually, yes. Housings and end plates are bored and faced back to true on our mills, and clearances are restored by machining or by repairing or replacing the rotors. We will tell you if the damage is too deep for the housing to be saved.

Do you balance the rotors during a rebuild?

Yes. Rotors are balanced during every rebuild and after any lobe repair. Imbalance is the most common reason a freshly rebuilt blower loses its bearings early.

Do you replace timing gears and reset the timing?

Yes. Timing gears are inspected for backlash and tooth wear, replaced when out of limit, and the rotors are retimed at assembly. Every clearance is double-checked after timing.

How long does a PD blower rebuild take?

It depends on the frame size, the damage found at teardown, and parts availability. Call with the make and model and we can give you a realistic estimate.

Talk to a Pump Expert

Get the answers you need from our experienced team. We’re here to help keep your operation running.

281-319-5595 Main Line

1-844-276-6274 1-844-276-NASH · Toll-Free

Down pump? Call Ken directly on the emergency line: 713-201-1589 or email Ken@precisemech.com.

Hours: Monday–Thursday, 7:00 AM–4:30 PM.

What to have ready: pump make, model, serial, and a photo of the nameplate.

Quick Links

Precise Mechanical

2414 Black Gold Ct,
Houston, TX 77073, USA

281-319-5595

1-844-276-6274 (NASH) Toll Free

Emergency Contact - Ken
713-201-1589
Ken@precisemech.com

Our Hours

Monday

7:00 - 4:30

Tuesday

7:00 - 4:30

Wednesday

7:00 - 4:30

Thursday

7:00 - 4:30

Friday

Closed

Saturday

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Sunday

Closed