Prop Pitch Gearbox

<body topmargin=0 leftmargin=0 marginheight=0 marginwidth=0> <table cellpadding=0 cellspacing=0 border=0><tr> <td valign="top" colspan=2 height=90 BGCOLOR="#006699" TEXT="#080000" bgproperties="fixed" background="002285a1erlcgo.png"> <div> <B>K7NV Prop Pitch Information</B></div> <div> <B>Small Prop Pitch</B><B> Speed Reducer</B><B>                                                                                                                                                                     </B></div> <div> </div> </td> </tr><tr> <td valign="top" width=210 BGCOLOR="#FFCC66" TEXT="#080000" background="001d2c00dkelyh.png"> <bR> <div> <A HREF="index.htm" TARGET="_top" TITLE="K7NV Prop Pitch Information"><U><B>Back to Prop Pitch Info Page</B></U></A></div> <bR> <bR> <div> <A HREF="id40.htm" TARGET="_top" TITLE="High Speed Planetary"><U><B>High Speed Planetary System</B></U></A></div> <bR> <div> <A HREF="id41.htm" TARGET="_top" TITLE="Low Speed Planetary"><U><B>Low Speed Planetary System</B></U></A></div> <bR> <div> <A HREF="id42.htm" TARGET="_top" TITLE="Gearbox Assembly"><U><B>Speed Reducer</B></U></A><A HREF="id42.htm" TARGET="_top" TITLE="Gearbox Assembly"><U><B> Assembly</B></U></A></div> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <div> Copyright © 2005</div> <div> Kurt Andress,  K7NV </div> <div> All Rights Reserved</div> </td> <td valign="top" height=390 BGCOLOR="#FFFFFF" TEXT="#080000"> <div> <B>The "Speed Reducer" is what most of us refer to as the prop pitch gearbox. This is not your Daddy's Tailtwister! It is a serious piece of aircraft quality equipment. </B></div> <bR> <div> <B>Below is a Curtiss-Wright diagram of an early model unit.</B></div> <bR> <bR> <DIV ALIGN="LEFT"></DIV> <div> <B><IMG SRC="17092920.jpg" border=0 width="658" height="914" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></B></div> <bR> <bR> <bR> <bR> <bR> <div> <B>The Gearbox Housings</B></div> <bR> <bR> <div> <B>The prop pitch Speed Reducer has a split case. The front and rear housings are bolted together with a ring gear, that is part of the low speed planetary system, in between them.</B></div> <bR> <DIV ALIGN="LEFT"></DIV> <div> <B><IMG SRC="0e7f4770.jpg" border=0 width="500" height="375" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"><IMG SRC="0e9f4770.jpg" border=0 width="500" height="375" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></B></div> <div> <B>Rear (Output) End Housing</B></div> <bR> <bR> <bR> <div> <B>Below is the Curtiss-Wright diagram of what goes into this half of the Speed Reducer.</B></div> <bR> <DIV ALIGN="LEFT"></DIV> <div> <B><IMG SRC="16e837a0.jpg" border=0 width="643" height="890" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></B></div> <bR> <div> <B>We don't need a lot of those parts at the upper end of the diagram to turn antennas.</B></div> <bR> <bR> <bR> <bR> <DIV ALIGN="LEFT"></DIV> <div> <B><IMG SRC="0ecf4770.jpg" border=0 width="500" height="375" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"><IMG SRC="0eef4770.jpg" border=0 width="500" height="375" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></B></div> <div> <B>Forward (Input) End of Late model Housing</B></div> <bR> <bR> <bR> <bR> <div> <B>Below is the Curtiss-Wright diagram of what goes into this housing. This an early model without jacks in the housing for power connections to the motor.</B></div> <bR> <bR> <DIV ALIGN="LEFT"></DIV> <div> <B><IMG SRC="16f84520.jpg" border=0 width="644" height="850" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></B></div> <bR> <bR> <div> <B><IMG SRC="0f058c20.jpg" border=0 width="600" height="450" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></B></div> <div> <B>Housings and Low Speed Planetary Ring Gear</B></div> <bR> <bR> <div> <B><IMG SRC="0f2f4770.jpg" border=0 width="500" height="375" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"><IMG SRC="0f4f4770.jpg" border=0 width="500" height="375" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></B></div> <div> <B>Assembled Housings with Ring Gear in Center.</B></div> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <div> <B>The Gear Train</B></div> <bR> <bR> <div> <B>The small, medium and large prop pitch units all use the same dual epicyclic (planetary) gear train configuration. Each of the two planetary systems, one high speed and one low speed, produce several gear reductions. This is a rather clever design producing a 9576:1 gear reduction in a very robust but small package for the torque it can produce when compared to the most common amateur antenna rotators.</B></div> <bR> <bR> <DIV ALIGN="LEFT"></DIV> <div> <B><IMG SRC="0c1bc0d0.jpg" border=0 width="700" height="525" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></B></div> <bR> <div> <B>This shows the assembled geartrain. The motor drives the shaft at the bottom and the output of the gearbox is the splined tube on top. The ring gear in the middle is sandwiched between the gearbox case halves.</B></div> <bR> <bR> <bR> <div> <B>Below is a sketch showing a cross section of the gear train without the top bell gear with splined tube.</B></div> <bR> <bR> <DIV ALIGN="LEFT"></DIV> <div> <B><IMG SRC="0c3204a0.jpg" border=0 width="800" height="1098" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></B></div> <div> <B><U>Note: </U></B><B>The reference to the 6203 bearings in the low speed planetary carrier does not mean that standard 6203 bearings will fit. The standard bearings are too thick and do not have a retaining ring groove. However the ID and OD of the special bearings that are in the carrier are the same. </B></div> <bR> <bR> <div> <B>Below is an early model gear train. The later ones have the same basic configuration. The early ones had a high speed planetary carrier that was one piece, machined out of aluminum. The later ones have a two piece carrier made out of forged steel. The drive shaft on the earlier ones had a slot at the motor connection end for the spade drive on the motor (like a flat blade screwdriver) .</B></div> <div> <B>The later versions used a splined connection. The axles for the two high speed planetary gears on the early models were removable shafts, on the later ones the axles were integral with the gears.</B></div> <bR> <bR> <DIV ALIGN="LEFT"></DIV> <div> <B><IMG SRC="16d8e880.jpg" border=0 width="654" height="904" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></B></div> <bR> <bR> <bR> <div> <B><IMG SRC="0c2bc0d0.jpg" border=0 width="700" height="525" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></B></div> <div> <B>Disassembled Gear Train</B></div> <bR> <div> <B>This photo shows the early model high speed planetary gears with the removeable axles. The basic dimensions and bearings, and fits for bearings were the same for early and later models, so the parts in most cases are interchangeable. The drive shafts for the different versions are not interchangeable because of the motor to drive shaft connection.</B></div> <bR> <bR> </td> </tr></table></body>