ADMA advises that Original Equipment Manufacturers of agricultural implements do the following:

  • Eliminate the need for PTO spline adaptors.
    • For implements designed to operate at one speed only, 540 rpm or 1,000 rpm; the operator's manual should clearly state to use the PTO driveshaft provided with the implement and no PTO adaptor may be used to alter speed or geometry.
  • Eliminate the need for PTO spline adaptors for implements designed to operate at either 540 rpm or 1,000 rpm.
    • Design implements and PTO driveshafts to fit all 3 types of PTO (1 3⁄8-6 spline at 540 rpm, 1 3⁄8-21 spline at 1,000 rpm and 1 3⁄4-20 spline at 1,000 rpm).
      Provide enough telescoping for PTO types 1, 2, and 3 drawbar length differences. Size joints large enough to handle highest torque. Design critical speed above all tractor PTO speeds.
  • Advise the end user if the PTO driveshaft can be modified on 1,000 rpm implements by changing the tractor end yoke from 1 3⁄8-21 spline to 13⁄4 -20 spline, or vice versa.
  • International safety standards state, "A sign shall be provided at a prominent location on the PTO-powered implement, near its PIC [Power Input Connection] specifying the nominal operating speed and the direction of rotation of the PTO driveshaft."
  • If the implement has high inertia, incorporate an integral overrunning clutch on the implement end of the PTO driveshaft.
  • Include the following information in the Implement Operators' Manual.
    • Never use a spline adaptor.
    • Match the right tractor PTO spline and speed with the PTO driveshaft provided with the
      implement. This will assure proper geometry and operating speed.
    • Never operate 540 rpm implements at 1,000 rpm.
    • Never operate 1,000 rpm implements at 540 rpm.
    • Provide information for the correct hitch geometry for each PTO type.
    • Use of adaptors will void warranty due to damage caused to the tractor PTO, PTO driveshaft or implement.
  • Based on the above information we advise that the use, promotion and/or selling of adaptors be discontinued.
  • ADMA recognizes this Design Guide does not cover every possible application and that the easy way to connect unmatched splines has been to use an adaptor. The use of an adaptor
    violates relevant safety standards and creates unacceptable guarding and operational hazards.


Members List

  Bondioli & Pavesi, Inc
Comer Industries
G&G Manufacturing Company
GKN Walterscheid, Inc.
Neapco Components, LLC
      Weasler Engineering,
Benzi America, Inc.