An internal gear pump uses an external gear that meshes inside an internal ring gear: oil is carried in the spaces between the teeth from suction to delivery. Thanks to the long contact between the teeth and to axial and radial gap compensation, it combines very low noise and pulsation with high pressures. That is why it is the reference pump for injection moulding machines, presses and servo pump drives.
The Hydraut range includes the Hydraut HIGP series and the Hytek HG and HGX series, from 4 to 180 cc/rev.
The range at a glance
| Series | Brand | Displacement (cc/rev) | Pressure nominal / peak (bar) | Max speed (rpm) | Fluids |
|---|
| HIGP | Hydraut | 4–180 | up to 315 / 350 | 3,000 | HLP, HFC, HEES, HFD-U |
| HG | Hytek | 8–180 | up to 315 / 350 | 3,000 | Mineral oil |
| HGX | Hytek | 8–180 | up to 315 / 350 | 3,000–4,000 | Mineral oil |
Alternative to Rexroth PGH, Voith IPV and Eckerle EIPH/EIPC
Our technical team has checked, model by model, the interchangeability of the Hytek HG and HGX series with the most common internal gear pumps on the market. These are the series equivalences validated so far:
| If you use | Hydraut proposes |
|---|
| Rexroth PGH | Hytek HG / HGX |
| Voith IPV | Hytek HG |
| Voith IPH | Hytek HG |
| Voith IPC | Hytek HG |
| Eckerle EIPH | Hytek HG |
| Eckerle EIPC | Hytek HG |
The Hytek HGX is the high-speed evolution of the HG: same pressures (315 bar nominal, 350 bar peak), speed up to 4,000 rpm on the HGX0, 3,500 on the HGX1 and 3,000 on the HGX2, validated by 600-hour endurance tests at 350 bar. The higher speed allows downsizing: the same flow from a smaller, lighter pump. Hytek is the No. 1 supplier of internal gear pumps for injection moulding machines in the Chinese market.
The exact equivalent code depends on displacement, flange, shaft, ports and direction of rotation: send us your code and we confirm it.
Internal gear pumps and servo pumps
Video: the Hytek HG internal gear pump in servo-drive applications (Hytek Power, 3:49).
In a servo pump the pump runs at variable speed, driven by a brushless motor and an inverter, and stops between cycles. An internal gear pump suited to servo drives, such as the HG, maintains volumetric efficiency also at low speed and eliminates flow control valves and discharge circuits. Our KSPH servo pump combines inverter, brushless motor and internal gear pump in twelve ready packages from 25 to 350 l/min, with energy savings of up to 80% in cycles with pauses and up to 20 dB less noise.
How to choose an internal gear pump
1. Continuous pressure, not only peak
Compare the nominal (continuous) pressure with the working pressure of the machine. In the HIGP and HG series the nominal pressure is 315 bar on most sizes and decreases on the largest displacement of each frame (down to 190 bar at 180 cc/rev): always check the specific size. The HGX has the same pressure ratings as the HG.
2. Speed and displacement
A higher maximum speed lets you reach the same flow with a smaller displacement. Calculate the flow as Q [l/min] = V [cc/rev] × n [rpm] / 1000.
3. Fluid
If the machine uses fire-resistant or biodegradable fluids (HFC, HFD-U, HEES), choose the HIGP series.
4. Single or double pump
Double pumps supply two circuits from one motor, for example the high-flow and the high-pressure stages of a press. Both HIGP and HG are available in single and double versions.
Rexroth, Voith, Eckerle and the series names mentioned are trademarks of their respective owners and are used only to indicate compatibility. Hydraut Europe S.r.l. is not affiliated with these companies.
