Spindle bearing arrangement for a power tool

Abstract

A power tool with a motor, a housing, a transmission, an output spindle, a front bearing and a rear bearing. The motor has an output shaft. The transmission is disposed in the housing and receives a rotary input from the output shaft. The transmission includes an input planetary stage, which has an input planet carrier, and an output planetary stage. The output spindle is driven by the transmission and has a first end, which extends at least partly through the input planetary stage, and a second end opposite the first end. The front bearing is disposed between the output spindle and the housing to support the second end of the output spindle for rotation about the spindle axis. The rear bearing indirectly supports the first end of the output spindle in the housing for rotation about the spindle axis.

What is claimed is: 
     
       1. A power tool comprising:
 a motor having an output shaft; 
 a housing; 
 a transmission in the housing and receiving a rotary input from the output shaft, the transmission comprising a planet carrier; 
 an output spindle driven by the transmission, the output spindle comprising a first end, which is supported for rotation about the spindle longitudinal axis by the planet carrier, and a second end opposite the first end, the second end extending from the housing and being adapted to drive a chuck into which a tool bit is removably received; 
 a first bearing engaging the housing and the planet carrier, the first bearing supporting the planet carrier for rotation about the spindle axis; and 
 a second bearing engaging the housing and the output spindle, the second bearing being configured to support the output spindle for rotation about the spindle longitudinal axis at a location nearer to the second end than the first end of the output spindle. 
 
     
     
       2. The power tool of  claim 1 , wherein the output shaft is received in the first end of the output spindle. 
     
     
       3. The power tool of  claim 1 , wherein a diameter of the first end is smaller than a diameter of a portion of the output shaft engaged by the first bearing. 
     
     
       4. The power tool of  claim 1 , further comprising a torque clutch that can cooperate with the transmission to limit an output torque of the power tool. 
     
     
       5. The power tool of  claim 4 , wherein the transmission further comprises a ring gear and wherein the torque clutch comprises a follower member that is biased into engagement with the ring gear to resist rotation of the ring gear relative to the housing. 
     
     
       6. The power tool of  claim 4 , wherein the torque clutch is disposed between the first and second ends of the output spindle. 
     
     
       7. The power tool of  claim 1 , wherein a spindle lock is mounted to the output spindle between the first and second ends. 
     
     
       8. The power tool of  claim 7 , wherein the spindle lock is mounted to a portion of the output spindle having a diameter that is different than a diameter of the first end and a diameter of the second end. 
     
     
       9. The power tool of  claim 1 , wherein the transmission comprises an output planetary stage and another planetary stage that is disposed between the motor and the output planetary stage, the planet carrier being associated with the another planetary stage. 
     
     
       10. The power tool of  claim 1 , wherein the transmission is a single speed transmission. 
     
     
       11. The power tool of  claim 1 , wherein the transmission includes a member that is movable between a first position and a second position, wherein the transmission operates in a first speed ratio to transmit rotary power when the member is in the first position, and wherein the transmission operates in a second, different speed ratio to transmit rotary power when the member is in the second position. 
     
     
       12. The power tool of  claim 11 , wherein the member is movable along a longitudinal axis of the transmission. 
     
     
       13. The power tool of  claim 12 , wherein the member is non-rotatably engaged to the first bearing when the member is in the first position. 
     
     
       14. The power tool of  claim 13 , wherein the member is a ring gear. 
     
     
       15. A power tool comprising:
 a motor having an output shaft; 
 a housing; 
 a transmission in the housing and receiving a rotary input from the output shaft, the transmission comprising a planet carrier; 
 a chuck; 
 an output spindle driven by the transmission, the output spindle comprising a first end, which is supported for rotation about the spindle longitudinal axis by the planet carrier, and a second end opposite the first end, the second end being mounted to the chuck; 
 a first bearing engaging the housing and the planet carrier, the first bearing supporting the planet carrier for rotation about the spindle axis; and 
 a second bearing engaging the housing and the output spindle, the second bearing being configured to support the output spindle for rotation about the spindle longitudinal axis at a location nearer to the second end than the first end of the output spindle; 
 wherein the transmission includes a member that is movable between a first position and a second position, wherein the transmission operates in a first speed ratio to transmit rotary power when the member is in the first position, and wherein the transmission operates in a second, different speed ratio to transmit rotary power when the member is in the second position; 
 wherein the member is movable along a longitudinal axis of the transmission; 
 wherein the member is non-rotatably engaged to the first bearing when the member is in the first position; and 
 wherein the first bearing comprises a first set of teeth and wherein the member comprises a second set of teeth that are engageable to the first set of teeth. 
 
     
     
       16. The power tool of  claim 12 , wherein the movable member is disposed between the first and second ends of the output spindle. 
     
     
       17. A power tool comprising:
 a motor having an output shaft; 
 a housing; 
 a transmission in the housing and receiving a rotary input from the output shaft, the transmission comprising an input stage and a planet carrier; 
 a chuck; 
 an output spindle driven by the transmission, the output spindle having a first end, which extends at least partly through the input stage, and a second end opposite the first end, the second end directly driving the chuck, the output spindle consisting of a single, continuous shaft member that extends between and includes the first and second ends; 
 a front bearing that engages the output spindle and the housing to support the second end of the output spindle for rotation about the spindle longitudinal axis; and 
 a rear bearing received in the housing and supporting an element of the transmission for rotation in the housing, the element of the transmission receiving the first end of the output spindle therein such that the rear bearing indirectly supports the first end of the output spindle in the housing for rotation about the spindle longitudinal axis. 
 
     
     
       18. The power tool of  claim 17 , wherein the first end of the output spindle is journally received into an element of the transmission. 
     
     
       19. The power tool of  claim 17 , wherein the element of the transmission comprises at least one of the planet carrier and a sun gear. 
     
     
       20. The power tool of  claim 17 , wherein a spindle lock is mounted to the output spindle between the first and second ends.