FCGear InvoluteRack: Difference between revisions
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#* Press the {{Button|[[File:FCGear_InvoluteRack.svg|16px]] [[FCGear_InvoluteRack|Involute Rack]]}} button in the toolbar. |
#* Press the {{Button|[[File:FCGear_InvoluteRack.svg|16px]] [[FCGear_InvoluteRack|Involute Rack]]}} button in the toolbar. |
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#* Select the {{MenuCommand|Gear → [[File:FCGear_InvoluteRack.svg|16px]] Involute Rack}} option from the menu. |
#* Select the {{MenuCommand|Gear → [[File:FCGear_InvoluteRack.svg|16px]] Involute Rack}} option from the menu. |
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# Change the gear parameter to the required conditions (see |
# Change the gear parameter to the required conditions (see [[#Properties|Properties]]). |
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==Properties== <!--T:8--> |
==Properties== <!--T:8--> |
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* {{PropertyData|add_endings|Bool}}: If {{Emphasis|True}}, then the total length of the rack is teeth * pitch, otherwise the rack starts with a tooth-flank. |
* {{PropertyData|add_endings|Bool}}: If {{Emphasis|True}}, then the total length of the rack is teeth * pitch, otherwise the rack starts with a tooth-flank. |
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* {{PropertyData|height|Length}}: Value of the gear width. |
* {{PropertyData|height|Length}}: Value of the gear width. |
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* {{PropertyData|module|Length}}: Module is the ratio of the reference diameter of the gear divided by the number of teeth (see |
* {{PropertyData|module|Length}}: Module is the ratio of the reference diameter of the gear divided by the number of teeth (see [[#Notes|Notes]]). |
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* {{PropertyData|teeth|Integer}}: Number of teeth. |
* {{PropertyData|teeth|Integer}}: Number of teeth. |
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* {{PropertyData|thickness|Length}}: Height from the tooth root to the lower side of the rod. |
* {{PropertyData|thickness|Length}}: Height from the tooth root to the lower side of the rod. |
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* {{PropertyData|transverse_pitch|Length}}: (read-only) Pitch in the transverse plane (see |
* {{PropertyData|transverse_pitch|Length}}: (read-only) Pitch in the transverse plane (see [[#Notes|Notes]]). |
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* {{PropertyData|beta|Angle}}: With the helix angle β a helical gear is created (positive value → rotation direction right, negative value → rotation direction left). |
* {{PropertyData|beta|Angle}}: With the helix angle β a helical gear is created (positive value → rotation direction right, negative value → rotation direction left). |
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* {{PropertyData|double_helix|Bool}}: {{Emphasis|True}} creates a double helix gear (see |
* {{PropertyData|double_helix|Bool}}: {{Emphasis|True}} creates a double helix gear (see [[#Notes|Notes]]) |
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* {{PropertyData|properties_from_tool|Bool}}: If helix angle β is given and {{Emphasis|properties_from-tool}} is enabled, gear parameters are internally recomputed for the rotated gear. |
* {{PropertyData|properties_from_tool|Bool}}: If helix angle β is given and {{Emphasis|properties_from-tool}} is enabled, gear parameters are internally recomputed for the rotated gear. |
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* {{PropertyData|pressure_angle|Angle}}: Default is 20° (see |
* {{PropertyData|pressure_angle|Angle}}: Default is 20° (see [[#Notes|Notes]]). |
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* {{PropertyData|clearance|Float}}: Default is 0,25 (see |
* {{PropertyData|clearance|Float}}: Default is 0,25 (see [[#Notes|Notes]]). |
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* {{PropertyData|head|Float}}: Default is 0,00. This value is used to change the tooth height. |
* {{PropertyData|head|Float}}: Default is 0,00. This value is used to change the tooth height. |
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Revision as of 17:44, 28 September 2022
FCGear InvoluteRack |
Menu location |
---|
Gear → Involute Rack |
Workbenches |
FCGear |
Default shortcut |
None |
Introduced in version |
v0.16 |
See also |
FCGear InvoluteGear |
Description
Gear racks are used to convert a rotary motion into a linear motion or vice versa. The following examples show the different applications:
- A rack with gear on at a retaining weir.
- Various rack systems of rack-and-pinion railways.
- Rack and pinion steering in a vehicle.
- Rack and pinion winch as mechanical hoist (e.g. car jack).
- Pneumatic rack and pinion drives used to control valves in pipeline transport.
From left to right: Spur gearing, helical gearing, double helical gearing
Usage
- Switch to the FCGear Workbench.
- There are several ways to invoke the command:
- Press the Involute Rack button in the toolbar.
- Select the Gear → Involute Rack option from the menu.
- Change the gear parameter to the required conditions (see Properties).
Properties
An FCGear InvoluteRack object is derived from a Part Feature object and inherits all its properties. It also has the following additional properties:
Data
base
- Dataadd_endings (
Bool
): If True, then the total length of the rack is teeth * pitch, otherwise the rack starts with a tooth-flank. - Dataheight (
Length
): Value of the gear width. - Datamodule (
Length
): Module is the ratio of the reference diameter of the gear divided by the number of teeth (see Notes). - Datateeth (
Integer
): Number of teeth. - Datathickness (
Length
): Height from the tooth root to the lower side of the rod.
computed
- Datatransverse_pitch (
Length
): (read-only) Pitch in the transverse plane (see Notes).
fillets
- Datahead_fillet (
Float
): - Dataroot_fillet (
Float
):
helical
- Databeta (
Angle
): With the helix angle β a helical gear is created (positive value → rotation direction right, negative value → rotation direction left). - Datadouble_helix (
Bool
): True creates a double helix gear (see Notes) - Dataproperties_from_tool (
Bool
): If helix angle β is given and properties_from-tool is enabled, gear parameters are internally recomputed for the rotated gear.
involute
- Datapressure_angle (
Angle
): Default is 20° (see Notes).
precision
- Datasimplified (
Bool
): True generates a simplified display (without teeth).
tolerance
- Dataclearance (
Float
): Default is 0,25 (see Notes). - Datahead (
Float
): Default is 0,00. This value is used to change the tooth height.
version
- Dataversion (
String
):
Notes
- transverse_pitch: The value is the result of multiplication of module * pi. This means for the standard involute rack of FCGear: 15 (teeth) * 3,14 (transverse_pitch) is 47.12 mm. See also module further below.
- clearance: At a gear pair, clearance is the distance between the tooth tip of the first gear and the tooth root of the second gear.
- double_helix: To use the double helical gearing the helix angle β (beta) for the helical gearing must first be entered.
- module: Using ISO (International Organization for Standardization) guidelines, Module size is designated as the unit representing gear tooth-sizes. Module (m): m = 1 (p = 3.1416), m = 2 (p = 6.2832), m = 4 (p = 12.566). If you multiply Module by Pi, you can obtain Pitch (p). Pitch is the distance between corresponding points on adjacent teeth. The result of the multiplication is displayed in transverse_pitch
- pressure_parameter: Only change the parameter, if sufficient knowledge of the gear geometry is available.
Useful formulas
See FCGear InvoluteGear.
Scripting
Use the power of python to automate your gear modeling:
import FreeCAD as App
import freecad.gears.commands
gear = freecad.gears.commands.CreateInvoluteRack.create()
gear.teeth = 20
gear.beta = 20
gear.height = 10
gear.double_helix = True
App.ActiveDocument.recompute()
Gui.SendMsgToActiveView("ViewFit")