diff --git a/freecad/gears/features.py b/freecad/gears/features.py
index 11f5bab..f3ef16c 100644
--- a/freecad/gears/features.py
+++ b/freecad/gears/features.py
@@ -490,9 +490,9 @@ class CycloidGear(BaseGear):
         obj.addProperty(
             "App::PropertyLength", "module", "gear_parameter", "module")
         obj.addProperty(
-            "App::PropertyLength", "inner_diameter", "cycloid_parameter", "inner_diameter (hypocycloid)")
+            "App::PropertyFloat", "inner_diameter", "cycloid_parameter", "inner_diameter divided by module (hypocycloid)")
         obj.addProperty(
-            "App::PropertyLength", "outer_diameter", "cycloid_parameter", "outer_diameter (epicycloid)")
+            "App::PropertyFloat", "outer_diameter", "cycloid_parameter", "outer_diameter divided by module (epicycloid)")
         obj.addProperty(
             "App::PropertyLength", "height", "gear_parameter", "height")
         obj.addProperty(
@@ -504,28 +504,32 @@ class CycloidGear(BaseGear):
         obj.addProperty("App::PropertyAngle", "beta", "gear_parameter", "beta")
         obj.addProperty(
             "App::PropertyLength", "backlash", "gear_parameter", "backlash in mm")
+        obj.addProperty(
+            "App::PropertyFloat", "head", "gear_parameter", "head_value * modul_value = additional length of head")
         obj.addProperty("App::PropertyPythonObject", "gear",
                         "gear_parameter", "the python object")
         obj.gear = self.cycloid_tooth
         obj.teeth = 15
         obj.module = '1. mm'
-        obj.inner_diameter = '5 mm'
-        obj.outer_diameter = '5 mm'
+        obj.inner_diameter = 7.5
+        obj.outer_diameter = 7.5
         obj.beta = '0. deg'
         obj.height = '5. mm'
         obj.clearance = 0.25
         obj.numpoints = 15
         obj.backlash = '0.00 mm'
         obj.double_helix = False
+        obj.head = 0
         obj.Proxy = self
 
     def execute(self, fp):
         super(CycloidGear, self).execute(fp)
         fp.gear.m = fp.module.Value
         fp.gear.z = fp.teeth
-        fp.gear.z1 = fp.inner_diameter.Value
-        fp.gear.z2 = fp.outer_diameter.Value
+        fp.gear.z1 = fp.inner_diameter
+        fp.gear.z2 = fp.outer_diameter
         fp.gear.clearance = fp.clearance
+        fp.gear.head = fp.head
         fp.gear.backlash = fp.backlash.Value
         fp.gear._update()
         pts = fp.gear.points(num=fp.numpoints)
diff --git a/pygears/cycloid_tooth.py b/pygears/cycloid_tooth.py
index 91d24dc..5234e9c 100644
--- a/pygears/cycloid_tooth.py
+++ b/pygears/cycloid_tooth.py
@@ -25,13 +25,14 @@ from ._functions import rotation, reflection
 
 
 class CycloidTooth():
-    def __init__(self, z1=5, z2=5, z=14, m=5, clearance=0.12, backlash=0.00):
+    def __init__(self, z1=5, z2=5, z=14, m=5, clearance=0.12, backlash=0.00, head=0.0):
         self.m = m
         self.z = z
         self.clearance = clearance
         self.backlash = backlash
         self.z1 = z1
         self.z2 = z2
+        self.head = head
         self._calc_gear_factors()
 
     def _calc_gear_factors(self):
@@ -39,7 +40,7 @@ class CycloidTooth():
         self.d2 = self.z2 * self.m
         self.phi = self.m * pi
         self.d = self.z * self.m
-        self.da = self.d + 2*self.m
+        self.da = self.d + 2*self.m + self.head * self.m
         self.di = self.d - 2*self.m - self.clearance * self.m
         self.phipart = 2 * pi / self.z
 
@@ -103,5 +104,5 @@ class CycloidTooth():
 
     def _update(self):
         self.__init__(m=self.m, z=self.z, z1=self.z1, z2=self.z2,
-                      clearance=self.clearance, backlash=self.backlash)
+                      clearance=self.clearance, backlash=self.backlash, head=self.head)