Eaton VIS 45 motors are commonly used in grapple rotate applications, however they are the open loop version of the motor which allows drifting in neutral do to the method used to lubricate the bearings and drive spline in the motor. This motor can be arranged as a closed loop motor which will provide proper lubriction and better load holding capability if plumbed correctly.  The complete write up is in this PDF file: Closed_Vs_Open_VIS

Here is an extract:

The Eaton VIS motor is commonly used in grapple rotate applications. The open loop version of the VIS in this application allows rotation drift do to the method used in providing lubrication oil for the inboard shaft bearing and drive splines. The method of lubrication relies on two check valves that seat inside of the valve star.  The port with the highest pressure provides the lubrication for the inboard bearing. The highest pressure unseats it’s ball in the star, and feeds the lubrication passage. The other check valve prevents flow from bypassing through both check valves.

There are two drawbacks to using the highest pressure port to provide the lubrication for the bearing: 1) the high pressure drop creates heat, and 2) When the control valve (in it’s neutral position) is used to hold a load, this load induced pressure is allowed to flow through the check, allowing the load to rotate.

 These motors can be converted to closed loop operation which will reduce the amount of drift experienced. At this time this idea is  theoretical and has not been tried in this application. Modifications of an OEM system may void warranties and must be done at the users own risk.Closed_Vs_Open_VIS

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Sergiy Sydorenko’s Insane Hydraulics:

http://www.insanehydraulics.com