diff --git a/src/specificClass.js b/src/specificClass.js
index 7dcc278..2979856 100644
--- a/src/specificClass.js
+++ b/src/specificClass.js
@@ -74,6 +74,16 @@ class MachineGroup {
         // Combination curve data
         this.dynamicTotals = { flow: { min: Infinity, max: 0 }, power: { min: Infinity, max: 0 } , NCog : 0};
         this.absoluteTotals = { flow: { min: Infinity, max: 0 }, power: { min: Infinity, max: 0 }};
+
+        // Dispatch serialization. PS ticks demand into MGC at 1 Hz, but
+        // a real pump ramp takes several seconds — without this gate
+        // every PS tick aborts the in-flight dispatch and starts a new
+        // one, so pumps never reach their setpoint. Mirrors
+        // rotatingMachine state.delayedMove: while a dispatch is in
+        // flight the latest demand is parked here for pickup when the
+        // current dispatch settles. Latest-wins.
+        this._dispatchInFlight = false;
+        this._delayedCall = null;
         //this always last in the constructor
         this.childRegistrationUtils = new childRegistrationUtils(this);
 
@@ -1274,6 +1284,37 @@ class MachineGroup {
 
     async handleInput(source, demand, powerCap = Infinity, priorityList = null) {
 
+        // Serialize dispatches: if a previous handleInput is still
+        // awaiting pump movements, park the latest demand and return.
+        // The in-flight dispatch's `finally` block will pick it up.
+        // See rotatingMachine state.delayedMove for the analogous
+        // pattern at the pump level.
+        if (this._dispatchInFlight) {
+            this._delayedCall = { source, demand, powerCap, priorityList };
+            this.logger.debug(`Dispatch in flight; deferring demand=${demand} until current pump moves complete.`);
+            return;
+        }
+
+        this._dispatchInFlight = true;
+        try {
+            return await this._runDispatch(source, demand, powerCap, priorityList);
+        } finally {
+            this._dispatchInFlight = false;
+            // Pick up the latest deferred call (intermediate values were
+            // stomped while we were busy — only the last one matters).
+            if (this._delayedCall) {
+                const next = this._delayedCall;
+                this._delayedCall = null;
+                this.logger.debug(`Dispatch finished; picking up deferred demand=${next.demand}.`);
+                // Recursive call re-enters the gate; safe because
+                // _dispatchInFlight has been reset to false above.
+                await this.handleInput(next.source, next.demand, next.powerCap, next.priorityList);
+            }
+        }
+    }
+
+    async _runDispatch(source, demand, powerCap = Infinity, priorityList = null) {
+
         const demandQ = parseFloat(demand);
 
         if(!Number.isFinite(demandQ)){