BarrettHand BH8-262 Lubrication

Each BarrettHand™ unit has been lubricated and tested prior to shipping. Periodically, lubrication must be reapplied to areas with high probability of lubricant flow. Use the grease syringe to apply Mobil 1® Synthetic Grease (both included with the maintenance kit) to all exposed gear teeth at the application points according to Figure 14 and the schedule in Table 6.


Issuing the following command to the hand will return the number of encoder counts, divided by 1000, on each motor.

fget od 

The number of joint cycles can be determined using the following conversions.

  • Fingers 1, 2, 3: (encoder counts) / 17,500
  • Spread: (encoder counts) / 3,100

Table 6 - Lubrication Schedule

Application PointMaintenance Cycle
Finger Worm Gears5000 cycles
Finger Spur Gears5000 cycles
Finger Motor Spur Gears5000 cycles
Palm Spur Gears5000 cycles


Figure 14 - Lubricant Application Points

Lubricating the finger spur gears requires caution, because you must remove each finger from the palm assembly to access this application point. See the section below on how to detach, lubricate, and reattach the finger.

Finger Replacement

Read all steps below before conducting this maintenance. Pogo pins that connect to sensors in the hand may shear unless the finger is detached and reattached with care. It is best to lubricate only one finger at a time.

Step 1: Turn off power to Hand.

Step 2: Open all fingers on the BarrettHand and open the Spread completely (fingers 1 and 2 opposite finger 3). The fingers can be opened manually using a 2 mm hex wrench in the right-hand hole shown. See Figure 15.


Figure 15: Prepare BarrettHand

Step 3: Locate shoulder screw that connects the finger to the hand. See Figure 16.


Figure 16: Locate shoulder screw

Step 4: Using a 2 mm hex wrench, unscrew the shoulder screw. Turn the hand sideways and slap the base of the BarrettHand with your palm to get the shoulder screw to fall out.

Step 5: Slide the finger assembly up slightly (Figure 17a), then pivot it out (Figure 17b).


Figure 17: Gently lift and rotate finger off

If the joint-torque sensor option is installed, BE CAREFUL not to damage the gold-plated electrical contact pins when disengaging the teeth. Do not twist or rock the finger when removing or attaching it.

Step 6: Slowly pull finger away from the motor body.


Figure 18: Slowly pull finger away from motor body.

Step 7: Take the replacement finger and verify that the inner link is driven into its stop. Using a 2 mm hex wrench, insert it into the right-hand hole and rotate counter-clockwise until the finger stops moving. See Figure 19.


Figure 19: Adjust angle of 2nd link.

Step 8: Check/adjust the angle of the fingertip using the plexiglass finger-angle tool. Place the tool as shown (Figure 20). Using a 2 mm hex wrench, insert it into the left-hand hole and rotate until the finger stops up against the forward edge of the plexiglass tool.

For BH8-262 hands only: Should either link, or the spur gears to which they are attached, move after the finger has been removed, the fingertip position must be reset. Use a 2-mm hex wrench to manually rotate the Joint-3 drive 5 1/2 revolutions from the position where both links are inline and horizontal.


Figure 20: Check/adjust the finger angle

Step 9: If necessary, add Mobil 1® Synthetic grease to the motor body cavity using the syringe provided. Cover all gear teeth with a thick bead of grease. Reverse Steps 5 and 6 to attach the new finger. Be careful not to damage (shear) the electrical ÒpogoÓ pins at the base of the motor (Figure 21).


Figure 21: Close-up of electrical "pogo" pins

Step 10: Once the finger is in place, apply slight pressure down and screw in the shoulder screw. See Figure 22.


Figure 22: Apply downwards pressure and secure shoulder screw.

Step 11: Verify that the finger operates smoothly. Using a 2mm hex wrench in the right-hand hole (see Figure Error: Reference source not found), drive the finger manually through its range of motion.

Finger replacement is complete.

Last modified 13 years ago Last modified on May 17, 2011, 9:33:02 PM