H673971 Case 1845C Hydraulic Drive Motor - 17-Tooth Spline - Low Speed High Torque 250cc - Replaces 229263A1

Hydraulic Drive Motor for Case 1845C — Replaces H673971

Direct replacement hydraulic drive motor for the legendary Case 1845C skid-steer loader. Low speed, high torque (LSHT) design — 250cc (15.2 cu in) displacement, 17-tooth spline shaft (1.5" diameter), 4-bolt magneto mount. Replaces Case part numbers H673971 and 229263A1. The same OEM-specification motor — at a fraction of the dealer price.

⚠️ This is the 17-tooth splined shaft version (newer model). If your 1845C has a keyed or tapered shaft motor, this is NOT the correct motor — please see our other listing or contact us to verify.

The Problem

Your Case 1845C is leaking hydraulic fluid from a drive motor, losing power to one side, or the machine is pulling hard in one direction. Drive motor failure on a 1845C means the skid steer is dead — you can't drive it, load it, or work it. Case dealers quote $1,400+ for the replacement motor, and wait times can be long for a machine this age. Meanwhile, your loader is parked, and the job it was doing isn't getting done. For farmers, landscapers, and small contractors, the 1845C is often the most essential machine on the property.

The Solution

This is the identical OEM-specification low speed, high torque hydraulic motor used to drive the Case 1845C. Same LSHT gerotor design, same 17-tooth spline shaft, same 4-bolt magneto mounting pattern — direct bolt-on replacement. The 250cc displacement delivers massive torque at low shaft speeds, which is exactly what a skid steer needs to turn its drive chains and push heavy loads. Replaces Case H673971 and superseded part number 229263A1. We offer it at $985 — saving you $400+ vs the dealer price.

Specifications

• Case OEM Part Number: H673971 (also 229263A1)
• Type: Low Speed High Torque (LSHT) Hydraulic Motor
• Design: Gerotor / orbital
• Displacement: 250cc (15.2 cu in)
• Shaft: 17-Tooth Spline, 1.5" Diameter
• Mount: 4-Bolt Magneto
• Ports: SAE O-ring hydraulic ports
• Application: Right or left track/wheel drive
• Condition: Brand New

⚠️ Shaft Type — Verify Before Ordering

The Case 1845C was produced for over a decade and uses two different drive motor shaft types depending on the serial number range:

• This listing: 17-Tooth Spline (1.5" diameter) — the newer, more common version
• Keyed / Tapered Shaft — older version, please see our other listing

To verify, look at your existing motor's output shaft. If it has splines (grooves around the circumference), this is the correct motor. If it has a smooth taper with a keyway, you need the tapered shaft version. Contact us with your serial number if you're unsure.

Identification

• Location: Mounted on each side of the machine frame — one motor per drive side
• Visual ID: Round motor housing bolted to the chain drive case, with a 17-tooth spline output shaft and two hydraulic hose connections
• Shaft Check: 17 spline teeth visible on the output shaft, 1.5" diameter
• Mount: 4-bolt magneto pattern
• Part Numbers: Check your Case parts manual for H673971 or 229263A1

Compatible Equipment

The H673971 / 229263A1 drive motor (17-tooth spline version) fits:

Case 1845C Skid-Steer Loader

• Case 1845C — later serial number ranges with 17-tooth spline shaft
• Left side drive motor
• Right side drive motor
• Both sides use the same motor (rotation is reversed by hydraulic flow direction)

Other Case Models (Verify PN)

• Case 1840 (select configurations — verify PN and shaft type)
• Case 1845B (verify PN — some share the motor)

⚠️ The Case 1845C uses the same motor on both left and right sides. Rotation direction is determined by which hydraulic port receives pressure, not by the motor itself. Always verify your part number AND shaft type before ordering.

Why Buy From Trenchwell?

• Save $400+: Case dealers charge $1,400+ for this motor. We offer the identical OEM-spec motor at $985 — same gerotor design, same 17-tooth spline shaft, massive savings.
• The Legend Deserves the Right Parts: The Case 1845C is the most popular skid steer ever built. Hundreds of thousands are still in daily use decades after production. They're indestructible — as long as you keep them maintained. This is the right motor to keep yours running.
• Same Motor, Both Sides: The 1845C uses the same drive motor on left and right. If one has failed, the other is likely on borrowed time. Consider ordering two and doing both at once — it's much easier while the machine is already torn down.
• OEM Specification: This is NOT a cheap import motor. This is the same LSHT gerotor motor designed for the 1845C drive system. 250cc displacement, 17-tooth spline shaft, 4-bolt magneto mount. Built by one of the world's leading hydraulic motor manufacturers.
• Expert Support: Not sure if you have the spline or tapered shaft version? Contact us with your Case serial number — we'll confirm the exact motor specification before you order.
• Fast Shipping: In stock and ready to ship.

Symptoms of a Failing Drive Motor

• Hydraulic fluid leaking from the motor shaft seal or housing
• Machine pulls to one side during travel (one side weaker than the other)
• One drive side noticeably slower than the other
• Loss of power or torque when pushing loads
• Grinding, whining, or knocking noise from the drive area
• Motor housing is excessively hot
• Complete loss of drive on one side
• Hydraulic system overheating (motor internal leakage dumps heat into the system)

Installation Notes

• Park on level ground, lower the bucket, shut off the engine, and set the parking brake
• Relieve all hydraulic pressure — cycle the controls with the engine off to bleed residual pressure
• Raise the machine and support it securely — you need the drive side off the ground
• Remove the tire/wheel to access the drive motor area
• Disconnect the two hydraulic lines from the motor — cap them immediately to prevent contamination
• Remove the 4 magneto mount bolts
• Slide the motor off the spline coupling — the 17-tooth spline should pull straight off
• Clean the spline coupling on the chain drive case
• Apply a thin coat of anti-seize to the spline teeth
• Align the new motor onto the 17-tooth spline and slide it into position
• Install and torque the 4 magneto mount bolts to spec (check your Case service manual)
• Reconnect the hydraulic lines — make sure you connect them to the correct ports
• Fill the motor case drain with clean hydraulic fluid (if applicable)
• Start the engine and slowly test drive operation — forward and reverse
• Check for leaks at all connections and the shaft seal
• Run both sides and verify equal speed and torque

Frequently Asked Questions

Is the left and right drive motor the same part?
Yes. The Case 1845C uses the same motor on both sides. The rotation direction is controlled by which port the hydraulic pump sends pressure to — not by the motor itself. So H673971 fits both left and right sides.

How do I tell if I have the spline or tapered shaft version?
Look at the output shaft of your existing motor. If it has grooves (teeth) around the circumference — that's a spline shaft, and this is the correct motor. If it's a smooth cone shape with a flat keyway cut into it — that's a tapered shaft, and you need the other version. You can also count the spline teeth — this motor has 17 teeth on a 1.5" diameter shaft.

My 1845C has 8,000 hours — is it worth replacing a drive motor?
Absolutely. The Case 1845C is one of the most durable skid steers ever made. Many are running with 10,000+ hours. Drive motors are a wear item — replacing one at $985 is far cheaper than replacing the entire machine. These loaders are worth maintaining.

Should I replace both motors at the same time?
If one has failed, the other has the same hours on it and is likely near the end of its life too. Replacing both while the machine is already torn down saves significant labor time. Contact us about pricing on a pair.

What does LSHT mean?
Low Speed, High Torque. These motors are designed to produce massive rotational force at slow shaft speeds — exactly what a skid steer needs to turn its drive chains and push heavy loads. The 250cc displacement means each revolution moves 250 cubic centimeters (15.2 cubic inches) of fluid, generating high torque even at low RPM.

How do I know if my motor is failing vs a hydraulic pump problem?
If BOTH sides are weak, it's more likely a pump or relief valve issue. If only ONE side is weak, slow, or leaking, it's almost certainly the drive motor on that side. External oil leaks from the motor housing are the most obvious sign of motor failure.