ISO 5675 Agricultural tractors and machinery – General purpose quick couplers

ISO 5675 standard specifies the essential interface dimensions and the operating requirements for hydraulic couplers employed to transmit hydraulic power from agricultural tractors to agricultural machinery. It is applicable to couplers used in hydraulic lines other than those used for braking circuits.

All hydraulic couplers are intended to be connected and disconnected frequently to allow the transfer of machinery from one tractor to another without the use of tools or special devices.

ISO 7241:2014, Hydraulic fluid power – Dimensions and requirements of quick-action couplings

ISO 18869:2017, Hydraulic fluid power – Test methods for couplings actuated with or without tools

Dimensional requirements

The dimensions of the coupler male part shall be in accordance with ISO 7241:2014,  “Series A“, for sizes 12,5 and 20. The coupler male part dimension shall also be in accordance with the additional dimension requirement. Additionally, a 15° angle shall be added in order to be compatible with dust protection devices.

ISO 5675 Additional Dimensional Requirements
Body Size
Body Size
12.5 1/2" ≤31 15˚±3˚
20 3/4" ≤38 15˚±3˚
The nominal size designation corresponds to the nominal inside diameter of the hose recommended for use with the coupling, as specified in ISO 4397.
Similar couplers are described in ISO 7241; however, couplers conforming to ISO 7241 might not conform to this document.
Coupler size 20 according to ISO 7241 is compatible to hose size 19 per ISO 4397

Operating requirements

  • The coupler shall be in accordance with the operating requirements of ISO 7241, “Series A‘ including the additional requirements for “Series N’ in ISO 7241.
  • The pressure drop through the coupler shall not be greater than 0,35 MPa with a flow of 45 l/ min for size 12,5 and 70 l/min for size 20. The pressure drop shall be measured in accordance with ISO 18869.
  • The fluid loss at an internal pressure of 0,1 MPa shall be in accordance with the table below. A fluid loss test shall be conducted in accordance with ISO 18869.
  • The fluid loss when disconnecting with an internal pressure of 17,5 MPa

Body Size
Body Size
Fluid Loss When disconnecting at
According to ISO 7241 0.1 Mpa 17.5 Mpa
12.5 1/2" 2.5 ml 4.0 ml a
20 3/4" 9.1 ml a 12.5 ml
  • The force required to fully open the valve in the coupler male part, when there is no internal pressure in the coupler male part, shall not exceed 45 N for sizes 12,5 and 70 N for size 20.
  • The coupling shall not check-off (closure of the valve) when oil flows in the male-to-female direction at flow rates less than 190 1/min for size 12,5 and less than 250 1/min for size 20.