6661022 Inline Case Drain Filter - Sintered Bronze 40 Micron - CTL / Skid Steer Final Drive - 1/4" NPT

Inline Case Drain Filter for Final Drive Motors — The #1 Insurance Policy for Your Track Loader

This is the single most important maintenance item on a compact track loader — and most operators don't even know it exists. The inline case drain filter catches metal particles that shed from your final drive motor before they circulate back into the hydraulic system. If this filter clogs, it WILL destroy your final drive. Replace it every time you service a final drive — no exceptions.

What Is a Case Drain Filter?

Every hydraulic motor has a "case drain" — a small 3rd line that returns leakage oil from inside the motor housing back to the hydraulic tank. As drive motors wear, they shed tiny metal flakes into this return oil. The case drain filter catches these particles before they contaminate the system. It's usually a small aluminum canister tucked behind a panel or buried in the engine bay — out of sight, out of mind. That's the problem.

The Failure Cascade

Here's what happens when the case drain filter clogs:

1. Filter Clogs: Metal particles from normal motor wear fill the sintered bronze element
2. Back-Pressure Builds: Oil can't drain from the motor housing, pressure builds inside
3. Shaft Seal Blows: The internal pressure blows out the main shaft seal — approximately $1,800 repair
4. Or Worse — Housing Cracks: In extreme cases, the pressure cracks the motor housing — total loss

A $65 filter prevents a $1,800–$4,000+ catastrophe. This is not optional maintenance.

⚠️ REQUIRED When Installing a New Final Drive

If you just bought a new final drive motor — you MUST install a new case drain filter at the same time. The old motor shed metal particles into the hydraulic system. Those particles are sitting in the case drain line and the old filter right now. If you connect a new motor to a contaminated system without replacing this filter, you will ruin the new motor in as little as 10 minutes of operation.

Specifications

• Type: Inline Case Drain Filter
• Element: Sintered Bronze (cone shape)
• Micron Rating: 40 Micron (industry standard for case drains)
• Pressure Rating: 3,000 PSI
• Port Size: 1/4" NPT
• Body: Aluminum canister
• Condition: Brand New

⚠️ Verify Your Line Size Before Ordering

• 1/4" NPT Line: This listing (most common on smaller CTLs and skid steers)
• 3/8" NPT Line: Contact us — we carry the 3/8" version for larger machines

Compatible Equipment

• Bobcat: S-Series skid steers, T-Series track loaders (replaces 6661022 assembly / 6661807 element)
• Takeuchi: TL130, TL230, TL12
• Gehl: CTL60, CTL70, CTL80
• Case: TR270, TR320, TV380
• New Holland: C-Series track loaders
• Kubota: SVL-Series track loaders
• Most CTLs and skid steers with 1/4" NPT case drain lines

When to Replace

• Every time you replace or rebuild a final drive motor — mandatory
• Every 1,000–1,500 operating hours as preventive maintenance
• Whenever you see metal particles in the hydraulic fluid or on magnetic drain plugs
• If the case drain line feels warm or bulges — indicates back-pressure

Why Buy From Trenchwell?

• $65 Prevents a $4,000 Catastrophe: There is no cheaper insurance policy for your track loader.
• Required for Warranty: Installing a new final drive without replacing this filter voids your warranty.
• Buy Two: You have two final drives — each has its own case drain filter. Service both sides.
• Fast Shipping: Ships with your final drive order.

Frequently Asked Questions

Can I clean the old filter and reuse it?
No. Sintered bronze filters cannot be effectively cleaned. Metal particles embed into the porous bronze. Replace it — at $65, it's not worth risking a $2,900+ motor.

What's the difference between 40 micron and 90 micron?
40 micron is the industry standard. 90 micron is used in very cold climates to prevent back-pressure from thicker oil. Normal conditions = 40 micron.

Do I need one filter per side?
Yes. Each final drive has its own case drain line and should have its own filter.