Beschrijving
This is the intelligent half of the cooling circuit. The motor downstream is fixed displacement and does exactly what it is told; this pump decides how much oil the fan actually gets, and it is controlled by the machine rather than by the engine speed. When a 345D runs hot with a healthy fan motor, this is usually where the story starts.
What Caterpillar says it is
295-9426 is listed as a pump group, piston type, and described in Caterpillar’s parts catalogue as an axial piston pump with variable displacement. The parallel reference 20R-0095 sits in the same catalogue family. It is bolted into the hydraulic pump train and driven mechanically, and its displacement is varied by a control that responds to the machine’s cooling demand.
The pairing that matters when you order
Two parts, one circuit, different symptoms. Getting them mixed up is the single most common error we see on CAT fan drive orders:
| Machine | Fan pump (supply side) | Fan motor (working side) |
|---|---|---|
| 345D, 345D L, 345D L VG | 295-9426 / 20R-0095 | 295-9429 / 311-9550 / 20R-0093 |
| 349D, 349D L | 295-9426 / 20R-0095 | 295-9429 / 311-9550 / 20R-0093 |
| 330D, 336D | 259-0815 / 10R-8707 | 234-4638 / 10R-8694 / 242-6776 |
| 325C, 322C | 200-3406 (gear pump) | 179-9778 / 20R-0121 |
| 330C | 194-8384 / 283-5992 | 191-5611 / 20R-0118 |
Numbers are quoted as they appear in Caterpillar catalogue references and established trade cross-references. On a machine of this value the serial prefix is still the final authority, and we check it before quoting.
Why variable displacement changes the diagnosis
Caterpillar’s specification for the 345D describes a cooling fan that is hydraulically driven with variable speed control based on ambient temperature, coolant temperature and hydraulic oil temperature. Three inputs means three ways for the system to be wrong without either hydraulic unit being faulty. A coolant sensor reading cold will hold the pump at minimum displacement on a machine that is actually overheating. A wiring fault to the proportional solenoid does the same thing more reliably. And a pump that has been running in hot, varnished oil will stick in part displacement, which is why a machine with a new motor and a new pump can still run hot.
So the order of work is: prove the command, then measure the delivery, then judge the unit. Our hydraulic fan pump diagnosis guide covers flow and pressure measurement, and the regulator diagnosis and adjustment article covers the control side. Coolant sensor testing is the cheapest check in the list and the one most often skipped.
Machine context
The 345D carries a Caterpillar C13 ACERT of 12.5 litre displacement producing 283 kW (380 hp) net flywheel power, with main system flow of 734 L/min and a cooling system holding 35.5 litre. The 349D shares the C13 and the 734 L/min figure, in a machine of roughly 46,300 kg depending on configuration. Those numbers are the reason a fan drive fault on this class of machine is a production problem within hours rather than days.
Fitting a replacement fan pump
- Compare the old and new units side by side before anything is cleaned up: shaft spline count and length, pilot diameter, mounting bolt pattern, port thread sizes and the orientation of the control.
- Fit a new return filter element and clear the suction strainer. Do not reuse oil that has already carried a pump’s worth of debris.
- Fill the pump casing with clean oil before cranking, and crack the suction line to purge air.
- Route the case drain to tank with no restriction, no check valve and no tight radius. Back-pressure in the casing is what pushes oil past the shaft seal.
- Confirm the control connector is seated and the wiring is sound before starting, not after.
- Bring the machine to temperature and prove the fan accelerates as demand rises. Log coolant and hydraulic oil temperature at low and high idle.
Cleanliness target for this class of axial piston unit is around ISO 4406 18/16/13 on Bosch Rexroth mobile hydraulics guidance. If the machine lost a pump before, read drive gear inspection en transfer case failure diagnosis before you assume the new pump is safe.
What we do not claim
We cannot confirm 295-9426 for the 345D2 or 349D2 Series 2 machines, and several suppliers wrongly list it for the 330D and 336D, which use the 259-0815 pump. If your plate reads something else, send the photograph.
Terms
Minimum order one piece; the mating motor is on our 295-9429 page. New aftermarket units carry a three to six month warranty as stated on your proforma invoice. Bench tested, photographed before packing, wooden case, delivery 5 to 8 working days from payment subject to stock. Full range under Caterpillar hydraulic fan motor.
