diff --git a/freecad/gears/bevelgear.py b/freecad/gears/bevelgear.py
index 91dd2ac..0862ccd 100644
--- a/freecad/gears/bevelgear.py
+++ b/freecad/gears/bevelgear.py
@@ -106,21 +106,21 @@ def __init__(self, obj):
         )
         obj.addProperty(
             "App::PropertyAngle",
-            "beta",
+            "helix_angle",
             "helical",
             QT_TRANSLATE_NOOP("App::Property", "angle used for spiral bevel-gears"),
         )
         obj.addProperty(
             "App::PropertyLength",
-            "dw",
+            "pitch_diameter",
             "computed",
             QT_TRANSLATE_NOOP("App::Property", "The pitch diameter."),
         )
         obj.setExpression(
-            "dw", "num_teeth * module"
+            "pitch_diameter", "num_teeth * module"
         )  # calculate via expression to ease usage for placement
         obj.setEditorMode(
-            "dw", 1
+            "pitch_diameter", 1
         )  # set read-only after setting the expression, else it won't be visible. bug?
         obj.addProperty(
             "App::PropertyAngle",
@@ -132,7 +132,7 @@ def __init__(self, obj):
             ),
         )
         obj.setExpression(
-            "angular_backlash", "backlash / dw * 360° / pi"
+            "angular_backlash", "backlash / pitch_diameter * 360° / pi"
         )  # calculate via expression to ease usage for placement
         obj.setEditorMode(
             "angular_backlash", 1
@@ -147,11 +147,42 @@ def __init__(self, obj):
         obj.numpoints = 20
         obj.backlash = "0.00 mm"
         obj.clearance = 0.1
-        obj.beta = "0 deg"
+        obj.helix_angle = "0 deg"
         obj.reset_origin = True
         self.obj = obj
         obj.Proxy = self
 
+    def onDocumentRestored(self, obj):
+        """  
+        backward compatibility functions
+        """
+        if hasattr(obj, "dw"):
+            pitch_diameter = getattr(obj, "dw")
+            obj.addProperty(
+                "App::PropertyLength",
+                "pitch_diameter",
+                "computed",
+                QT_TRANSLATE_NOOP("App::Property", "The pitch diameter."),
+                1,
+            )
+            obj.pitch_diameter = pitch_diameter
+            obj.removeProperty("dw")
+            obj.setExpression(
+                "angular_backlash", "backlash / pitch_diameter * 360° / pi"
+            )
+
+        # replace beta with helix_angle
+        if hasattr(obj, "beta"):
+            helix_angle = getattr(obj, "beta")
+            obj.addProperty(
+                "App::PropertyAngle",
+                "helix_angle",
+                "helical",
+                QT_TRANSLATE_NOOP("App::Property", "helix angle"),
+            )
+            obj.helix_angle = helix_angle
+            obj.removeProperty("beta")
+
     def generate_gear_shape(self, fp):
         fp.gear.z = fp.num_teeth
         fp.gear.module = fp.module.Value
@@ -189,7 +220,7 @@ def generate_gear_shape(self, fp):
         else:  # starting with version 0.0.2
             scale_0 = scale - fp.height.Value
             scale_1 = scale
-        if fp.beta.Value == 0:
+        if fp.helix_angle.Value == 0:
             wires.append(make_bspline_wire([scale_0 * p for p in pts]))
             wires.append(make_bspline_wire([scale_1 * p for p in pts]))
         else:
@@ -198,7 +229,7 @@ def generate_gear_shape(self, fp):
                 # rot = rotation3D(- beta_i)
                 # points = [rot(pt) * scale_i for pt in pts]
                 angle = (
-                    fp.beta.Value
+                    fp.helix_angle.Value
                     * np.pi
                     / 180.0
                     * np.sin(np.pi / 4)
diff --git a/freecad/gears/connector.py b/freecad/gears/connector.py
index 573f579..f27aa18 100644
--- a/freecad/gears/connector.py
+++ b/freecad/gears/connector.py
@@ -115,9 +115,9 @@ def onChanged(self, fp, prop):
             angle_master = fp.master_gear.Placement.Rotation.Angle * sum(
                 fp.master_gear.Placement.Rotation.Axis
             )
-            dw_master = fp.master_gear.dw
-            dw_slave = fp.slave_gear.dw
-            dist = (dw_master + dw_slave) / 2
+            pitch_diameter_master = fp.master_gear.pitch_diameter
+            pitch_diameter_slave = fp.slave_gear.pitch_diameter
+            dist = (pitch_diameter_master + pitch_diameter_slave) / 2
             if fp.master_gear.shift != 0 or fp.slave_gear.shift != 0:
                 dist, alpha_w = compute_shifted_gears(
                     fp.master_gear.module,
@@ -132,8 +132,8 @@ def onChanged(self, fp, prop):
             trans = app.Vector(dist)
             mat0.move(trans)
             rot = app.Rotation(app.Vector(0, 0, 1), fp.angle1).toMatrix()
-            angle2 = dw_master / dw_slave * fp.angle1.Value
-            angle4 = dw_master / dw_slave * np.rad2deg(angle_master)
+            angle2 = pitch_diameter_master / pitch_diameter_slave * fp.angle1.Value
+            angle4 = pitch_diameter_master / pitch_diameter_slave * np.rad2deg(angle_master)
             rot2 = app.Rotation(app.Vector(0, 0, 1), angle2).toMatrix()
             angle3 = abs(fp.slave_gear.num_teeth % 2 - 1) * 180.0 / fp.slave_gear.num_teeth
             rot3 = app.Rotation(app.Vector(0, 0, 1), angle3).toMatrix()
@@ -148,9 +148,9 @@ def onChanged(self, fp, prop):
             angle_master = fp.master_gear.Placement.Rotation.Angle * sum(
                 fp.master_gear.Placement.Rotation.Axis
             )
-            dw_master = fp.master_gear.dw
-            dw_slave = fp.slave_gear.dw
-            dist = (dw_master - dw_slave) / 2
+            pitch_diameter_master = fp.master_gear.pitch_diameter
+            pitch_diameter_slave = fp.slave_gear.pitch_diameter
+            dist = (pitch_diameter_master - pitch_diameter_slave) / 2
             if fp.master_gear.shift != 0 or fp.slave_gear.shift != 0:
                 dist, alpha_w = compute_shifted_gears(
                     fp.master_gear.module,
@@ -165,8 +165,8 @@ def onChanged(self, fp, prop):
             trans = app.Vector(dist)
             mat0.move(trans)
             rot = app.Rotation(app.Vector(0, 0, 1), fp.angle1).toMatrix()
-            angle2 = -dw_master / dw_slave * fp.angle1.Value
-            angle4 = -dw_master / dw_slave * np.rad2deg(angle_master)
+            angle2 = -pitch_diameter_master / pitch_diameter_slave * fp.angle1.Value
+            angle4 = -pitch_diameter_master / pitch_diameter_slave * np.rad2deg(angle_master)
             rot2 = app.Rotation(app.Vector(0, 0, 1), angle2).toMatrix()
             angle3 = abs(fp.slave_gear.num_teeth % 2 - 1) * 180.0 / fp.slave_gear.num_teeth
             rot3 = app.Rotation(app.Vector(0, 0, 1), angle3).toMatrix()
@@ -185,15 +185,15 @@ def onChanged(self, fp, prop):
             angle_master = fp.master_gear.Placement.Rotation.Angle * sum(
                 fp.master_gear.Placement.Rotation.Axis
             )
-            dw_master = fp.master_gear.dw.Value
-            dw_slave = 0
-            dist = -(dw_master + dw_slave) / 2
+            pitch_diameter_master = fp.master_gear.pitch_diameter.Value
+            pitch_diameter_slave = 0
+            dist = -(pitch_diameter_master + pitch_diameter_slave) / 2
             mat0 = app.Matrix()  # unity matrix
             mat0.move(app.Vector(dist, 0, 0))
             mat1 = app.Matrix()
-            mat1.move(app.Vector(0, np.deg2rad(fp.angle1.Value) * dw_master / 2, 0))
+            mat1.move(app.Vector(0, np.deg2rad(fp.angle1.Value) * pitch_diameter_master / 2, 0))
             mat2 = app.Matrix()
-            mat2.move(app.Vector(0, -np.deg2rad(fp.angle2.Value) * dw_master / 2, 0))
+            mat2.move(app.Vector(0, -np.deg2rad(fp.angle2.Value) * pitch_diameter_master / 2, 0))
             rot = app.Rotation(app.Vector(0, 0, 1), fp.angle1).toMatrix()
             mat3 = rot * mat2 * mat1 * mat0
             mat3.move(fp.master_gear.Placement.Base)
@@ -205,15 +205,15 @@ def onChanged(self, fp, prop):
             angle_master = fp.master_gear.Placement.Rotation.Angle * sum(
                 fp.master_gear.Placement.Rotation.Axis
             )
-            dw_master = fp.master_gear.dw
-            dw_slave = fp.slave_gear.dw
-            dist = (dw_master + dw_slave) / 2
+            pitch_diameter_master = fp.master_gear.pitch_diameter
+            pitch_diameter_slave = fp.slave_gear.pitch_diameter
+            dist = (pitch_diameter_master + pitch_diameter_slave) / 2
             mat0 = app.Matrix()  # unity matrix
             trans = app.Vector(dist, 0, 0)
             mat0.move(trans)
             rot = app.Rotation(app.Vector(0, 0, 1), fp.angle1).toMatrix()
-            angle2 = dw_master / dw_slave * fp.angle1.Value
-            angle4 = dw_master / dw_slave * np.rad2deg(angle_master)
+            angle2 = pitch_diameter_master / pitch_diameter_slave * fp.angle1.Value
+            angle4 = pitch_diameter_master / pitch_diameter_slave * np.rad2deg(angle_master)
             rot2 = app.Rotation(app.Vector(0, 0, 1), angle2).toMatrix()
             angle3 = abs(fp.slave_gear.num_teeth % 2 - 1) * 180.0 / fp.slave_gear.num_teeth
             rot3 = app.Rotation(app.Vector(0, 0, 1), angle3).toMatrix()