The subject matter of this specification can be embodied in, among other things, a method that includes controlling, by a first fluid valve, a first fluid flow to a first fluid actuator, actuating, by the first fluid actuator, an output, controlling, by a second fluid valve, a second fluid flow to a second fluid actuator, and actuating, by the second fluid actuator, the output.

The subject matter of this specification can be embodied in, among other things, an apparatus that includes a first assembly having a first piston rod having a first rod end, a second assembly arranged substantially parallel to the first piston assembly and having a second piston rod having a second rod end, an end assembly defining a first aperture configured to receive the first rod end, and a second aperture configured to receive the second rod end, a first retaining cap configured to affix to the first rod end, abut the end assembly when affixed to the first rod end, and retain the first rod end within the first aperture, and a second retaining cap configured to affix to the second rod end, abut the end assembly when affixed to the second rod end, and retain the second rod end within the second aperture.