diff --git a/freecad/gears/bevelgear.py b/freecad/gears/bevelgear.py
index ef0768f..91dd2ac 100644
--- a/freecad/gears/bevelgear.py
+++ b/freecad/gears/bevelgear.py
@@ -95,7 +95,7 @@ def __init__(self, obj):
             "tolerance",
             QT_TRANSLATE_NOOP(
                 "App::Property",
-                "The arc length on the pitch circle by which the tooth thicknes is reduced.",
+                "The arc length on the pitch circle by which the tooth thickness is reduced.",
             ),
         )
         obj.addProperty(
diff --git a/freecad/gears/cycloidgear.py b/freecad/gears/cycloidgear.py
index b3cc708..2a3c5f9 100644
--- a/freecad/gears/cycloidgear.py
+++ b/freecad/gears/cycloidgear.py
@@ -172,7 +172,7 @@ def add_tolerance_properties(self, obj):
             "tolerance",
             QT_TRANSLATE_NOOP(
                 "App::Property",
-                "The arc length on the pitch circle by which the tooth thicknes is reduced.",
+                "The arc length on the pitch circle by which the tooth thickness is reduced.",
             ),
         )
         obj.addProperty(
diff --git a/freecad/gears/internalinvolutegear.py b/freecad/gears/internalinvolutegear.py
index 51671ec..8a3255d 100644
--- a/freecad/gears/internalinvolutegear.py
+++ b/freecad/gears/internalinvolutegear.py
@@ -258,7 +258,7 @@ def add_tolerance_properties(self, obj):
             "tolerance",
             QT_TRANSLATE_NOOP(
                 "App::Property",
-                "The arc length on the pitch circle by which the tooth thicknes is reduced.",
+                "The arc length on the pitch circle by which the tooth thickness is reduced.",
             ),
         )
         obj.addProperty(
diff --git a/freecad/gears/involutegear.py b/freecad/gears/involutegear.py
index 6d98c7d..3c09ea7 100644
--- a/freecad/gears/involutegear.py
+++ b/freecad/gears/involutegear.py
@@ -312,7 +312,7 @@ def add_tolerance_properties(self, obj):
             "tolerance",
             QT_TRANSLATE_NOOP(
                 "App::Property",
-                "The arc length on the pitch circle by which the tooth thicknes is reduced.",
+                "The arc length on the pitch circle by which the tooth thickness is reduced.",
             ),
         )
         obj.addProperty(
diff --git a/freecad/gears/involutegearrack.py b/freecad/gears/involutegearrack.py
index 8c7078c..88daa65 100644
--- a/freecad/gears/involutegearrack.py
+++ b/freecad/gears/involutegearrack.py
@@ -123,7 +123,7 @@ def add_helical_properties(self, obj):
             "App::PropertyAngle",
             "helix_angle",
             "helical",
-            QT_TRANSLATE_NOOP("App::Property", "helix anglle"),
+            QT_TRANSLATE_NOOP("App::Property", "helix angle"),
         )
         obj.addProperty(
             "App::PropertyBool",
diff --git a/freecad/gears/timinggear_t.py b/freecad/gears/timinggear_t.py
index 43cff5a..47513b0 100644
--- a/freecad/gears/timinggear_t.py
+++ b/freecad/gears/timinggear_t.py
@@ -65,7 +65,7 @@ def __init__(self, obj):
             "tolerance",
             QT_TRANSLATE_NOOP(
                 "App::Property",
-                "The arc length on the pitch circle by which the tooth thicknes is reduced.",
+                "The arc length on the pitch circle by which the tooth thickness is reduced.",
             ),
         )
         obj.addProperty(