What an Electric Trochoid Oil Pump Is
A trochoid pump is an internal-gear pump: an outer rotor and an inner rotor with one less tooth trap oil between them and carry it from suction to discharge. An electric motor on the same shaft drives the set at 1400 rpm. In this series the result is twelve close-coupled motor-pump kits, from the 43724-1 up to the 43725-6, aimed at machine-tool lubrication, cooling and circulation, and low-pressure oil transfer.
Model Range
Discharge rises with model size in both series, and each 43724 model pairs with a 43725 model of identical hydraulic output.
| Model | Discharge (L/min) | Ports | Mounting footprint (mm) | Length (mm) |
|---|---|---|---|---|
| 43724-1 | 1.2 | Rc1/8 | 61 | 266 |
| 43724-2 | 1.9 | Rc1/4 | 61 | 269 |
| 43724-3 | 3.0 | Rc1/4 | 61 | 273 |
| 43724-4 | 4.2 | Rc3/8 | 64 | 278 |
| 43724-5 | 5.0 | Rc3/8 | 64 | 280 |
| 43724-6 | 6.0 | Rc3/8 | 64 | 285 |
| 43725-1 | 1.2 | Rc1/8 | 61 | 248 |
| 43725-2 | 1.9 | Rc1/4 | 61 | 251 |
| 43725-3 | 3.0 | Rc1/4 | 61 | 255 |
| 43725-4 | 4.2 | Rc3/8 | 64 | 258 |
| 43725-5 | 5.0 | Rc3/8 | 64 | 262 |
| 43725-6 | 6.0 | Rc3/8 | 64 | 267 |
Declared Specifications
| Item | Specification |
|---|---|
| Motor power | 120 W |
| Speed | 1400 rpm |
| Current | 0.83 A at 220V; 0.48 A at 380V |
| Rated pressure | 0.4 MPa |
| Maximum pressure | 0.5 MPa |
| Safety valve | Adjustable 0-0.4 MPa on 43724; fixed on 43725 |
| Oil viscosity | 20-320 cSt |
| Ambient temperature | -10°C to +50°C |
| Oil temperature | +5°C to +80°C |
| Suction strainer | 100-150 micron before the rotor chamber |
| Mounting | Horizontal or vertical, suction port down for priming |
| Rotation | Clockwise; verify on wiring |
The tapered Rc ports follow the JIS B 0203 thread form.
What Internal-Gear Geometry Buys
The rotors move oil in a continuous transfer action rather than the pulsing trapping of external gears, so flow is smooth and noticeably quieter than external-gear pumps of similar size. The design also self-primes, because the expanding cavity at the suction side pulls oil in without a separate priming device. In practice that means steadier feeding of lubrication points and tolerance of positions where the pump sits briefly above the oil level. For the sibling pump family on this site, see the BRB trochoid pump; the trochoid pump guide covers operating theory in long form.
Choosing Between the Two Series
The 43724 and 43725 series differ in exactly one place: the safety valve. Series 43724 carries an adjustable safety valve settable across 0-0.4 MPa, so the circuit pressure limit can be tuned to the machine. Series 43725 carries a fixed valve, rated 0.4 MPa with a 0.5 MPa maximum. Every other entry in the model table pairs identically: discharge, ports, footprint, length, and motor. Decide the valve question first, and the rest of the selection reduces to flow. These kits sit within the wider oil pump range on this site, alongside units like the 2 L automatic oil pump and the electromagnetic piston oil pump.
Installing and Integrating
Wire the motor to your supply, 220V or 380V three-phase, configured per the nameplate, and confirm clockwise rotation after wiring rather than assuming it. Mount horizontally or vertically with the suction port down for priming. Fit a suction strainer of 100-150 micron before the rotor chamber, because the tight rotor clearances that make the pump quiet also make it vulnerable to debris. Seal the Rc tapered threads appropriately, keep the oil within 20-320 cSt and +5°C to +80°C, and the pump will behave as declared. In a full single-line lubrication system, this pump sits upstream of the metering devices that split flow to each point.
Questions about voltage configuration or the right model for your machine? Ask through our contact page.
Frequently Asked Questions
What does trochoid mean?
It describes an internal-gear rotor set, with one less tooth on the inner rotor. This geometry moves oil smoothly with low pulsation.
Which series should I pick?
The only difference is the safety valve. Choose 43724 for adjustable 0-0.4 MPa, or 43725 for fixed pressure.
What flow size do I need?
Match the machine builder’s required flow rather than oversizing. The range spans 1.2 to 6.0 L/min.
Should I wire it for 220V or 380V?
Your supply and the motor nameplate decide. Confirm the winding configuration and rotation direction after wiring.
Can it pump grease?
No, these kits pump oil from 20 to 320 cSt. Grease requires a different pump type.
Is it self-priming?
The internal-gear design self-primes well. Flooded suction is still preferred for reliable starting.
What does a kit include?
The motor-pump assembly, plus the safety valve on 43724. Confirm fittings and accessories per quotation.
What maintenance is needed?
Keep the oil clean and check the suction strainer. Watch for rising noise or falling flow.
Who can help me choose a model?
Ask about model selection through our contact page. Include the required flow, voltage, and oil viscosity.
Who builds and supports these kits?
IsoHiTech Lubrication Systems, founded in 2023, engineering since 2006, builds and supports every unit. Email inquiry@isohitech.com for specifications and a quotation.
