Rocketbox PTO - 8.45:1

The Rocketbox PTO is a shifting transmission designed to send power out to either of two output shafts, independently. PTO stands for "Power Take Off" and is a term commonly used for mechanisms which can switch supplied power from one shaft over to another. On our Rocketbox, one shaft is intended to provide power to a robot drivetrain (aka: Drive Output Shaft) while the second shaft may power separate appendage, arm, winch, or any other mechanism (aka: Mechanism Shaft). Both output shafts cannot be powered at the same time.

Gears can be swapped in and out on the second stage of the Rocketbox PTO, much like our Toughbox Mini. To change ratios, simply change the small cluster gear and the large output gear that is on the shifting shaft.

This transmission is shipped assembled, not as a kit. However, this transmission has the ability to be rebuilt into a mirror image of itself. The side plates are identical and reversible, allowing users to have concentric Mechanism Shafts when installed on each side of the drivetrain. Also unique to this transmission is the inclusion of a spring-extended air cylinder which performs the shifting action. This cylinder requires air pressure to actuate the dog shifting mechanism to transmit torque from the Drive Output Shaft or the Mechanism Shaft.

Key Features:

• Two output shafts (Drive Shaft and Mechanism Shaft) positioned on opposite sides of the transmission are utilized, with only one driven at a time
• One or two CIM Motor input
• Wide variety of gear ratio and shaft options available
• Can be reassembled in mirrored geometry
• Air cylinder included
  

Shift Style:
Due to the large amount of forces and torques involved in shifting this PTO, pneumatic shifting is recommended. The spring extended, Bimba model.
040.5-RP Air Cylinder with nut (am-0591) is the preferred cylinder for this transmission. If air pressure is lost, the spring pushes the cylinder and dog shift gear into the Drive Output Shaft on the plate opposite from the motors. This shift method actuates in under 0.5 seconds, with 26 pounds of force (if using 60 psi). This pneumatic shift can be done while the transmission is accelerating or decelerating.


Gear Stages and Ratios:
This transmission consists of three gear stages:

1. The first stage includes two 14T CIM gears (am-0034) and a 50T Cluster Gear (am-0149)
2. The second stage is where the gears can be changed to provide various gear ratios. The customer can order one ratio and then purchase extra, optional gears in order to get different ratios. Final output ratios are listed here (with the second stage gear pair):
   • 5.95:1 (24T and 40T), am-3343_59
   • 7.31:1 (21T and 43T), am-3343_73
   • 8.45:1 (19T and 45T), am-3343_84
   • 10.71:1 (16T and 48T), am-3343_107
   • 12.71:1 (14T and 50T), am-3343_127
3. The third stage transmits power from the shifting shaft onto either of the output shafts. This ratio is 1:1, with 35T gears on both shafts. The dog shifter on the shifting shaft selects which output shaft to send power.

Product Usage:
All AndyMark gearboxes require grease for proper operation and long life. We suggest using our red tacky grease, am-2768. We also encourage that the user powers the gearbox continuously for 30 minutes without grease to allow the gear teeth to wear in. While we do design with short run times in mind, this 'run in' period for smooth gearbox operation, is recommended. Once this is completed, thorough grease of the gear teeth periodically to ensure smooth operation.