diff --git a/src/main/java/org/grobid/core/utilities/UnitUtilities.java b/src/main/java/org/grobid/core/utilities/UnitUtilities.java
index 15b1951a..34c577f9 100644
--- a/src/main/java/org/grobid/core/utilities/UnitUtilities.java
+++ b/src/main/java/org/grobid/core/utilities/UnitUtilities.java
@@ -111,7 +111,8 @@ public enum Unit_Type {
         ATOMIC_RATIO("atomic ratio"),
         WEIGHT_RATIO("weight ratio"),
         MASS_ACCUMULATION_RATE("mass accumulation rate"),
-        SEDIMENTATION_RATE("sedimentation rate");;
+        SEDIMENTATION_RATE("sedimentation rate"),
+        ROTATION("rotation");
 
         private String name;
 
diff --git a/src/main/resources/lexicon/en/units.json b/src/main/resources/lexicon/en/units.json
index 06e64620..36d5b3da 100644
--- a/src/main/resources/lexicon/en/units.json
+++ b/src/main/resources/lexicon/en/units.json
@@ -1347,6 +1347,9 @@
         {
           "raw": "rpm"
         },
+        {
+          "raw": "RPM"
+        },
         {
           "raw": "round/min",
           "product": [
@@ -1358,9 +1361,33 @@
               "pow": "-1"
             }
           ]
+        },
+        {
+          "raw": "rev/min",
+          "product": [
+            {
+              "base": "rev"
+            },
+            {
+              "base": "min",
+              "pow": "-1"
+            }
+          ]
+        },
+        {
+          "raw": "r/min",
+          "product": [
+            {
+              "base": "r"
+            },
+            {
+              "base": "min",
+              "pow": "-1"
+            }
+          ]
         }
       ],
-      "type": "FREQUENCY",
+      "type": "ROTATION",
       "system": "NON_SI",
       "names": [
         {
@@ -1368,6 +1395,9 @@
           "inflections": [
             "rounds per minute"
           ]
+        },
+        {
+          "lemma": "number of revolutions"
         }
       ]
     },