Hydraulic Couplers and Flow Rate

Couplers are the connection point that allows hydraulic fluid to flow between the host machine and the attachment, powering the hydraulic function of the attachment. Attachment compatibility depends on the quick couplers being the same size and kind and the auxiliary hydraulic flow rate of the machine being within the attachment's recommended hydraulic flow range. Use the Flow Rate Finder below to find your machine's flow rate and determine if it is within the accepted range of a certain attachment.

Hydraulic Flow Finder

Enter your machine information below to determine its flow rate. For skid steers please make sure to specify if you machine is the standard or high flow version.

Types of Hydraulic Couplers

Flat Face Couplers

Flat face couplers are the standard couplers that most skid steers and mini excavators are equipped with these days. The male and female are both flat on the end and simply push together to form the connection. Sizes include 1/2" for standard flow machines, 3/4" for high flow machines (5/8" less common for high flow machines), and 3/8" for case drains.

Pioneer Couplers

On most machines made prior to 1996, Pioneer style couplers are used. Pioneer couplers have also been used on older tractor equipment. The male end has a nipple protruding out of the end. The female end has a hole that has a ring of ball bearings around it.

Case Drain Couplers

Case drains are required on some attachments to relieve excess oil pressure from the motor seals. On these attachments there is a third hydraulic hose with a smaller 3/8” body coupler.

Typically, high flow Skid Steers and Excavators are equipped with a Male 3/8” Body coupler as the case drain coupler. In this case, when you are buying an attachment, you will select the Female 3/8” Body coupler to go onto the attachment.

If your machine is equipped with a Female 3/8” body coupler instead, then you will need to specify a Male 3/8” body coupler when purchasing these attachments.