Cabin Systems: Hydrolok

Brand Expertise: P.L. PORTER

Cabin Systems: Hydrolok

Brand Expertise: P.L. PORTER

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Hydrolok Hydraulic Seat Recline Devices

The Hydrolok® has been an aerospace industry standard for aircraft seats since its introduction in 1947. Customers know they can rely on the strong, long-lasting Hydrolok even in tough usage situations. The Hydrolok offers infinite adjustment options, requires almost no maintenance and can last up to 250,000 cycles for the lowest total cost of ownership to operators.

The Hydrolok family can go on any seat in an aircraft regardless of allowable recline. This makes it easy for operators to reconfigure the cabin or refurbish older seats. Hydroloks are a drop-in replacement for virtually all existing mechanical or gas locks, saving valuable time and labor. Its low activation force is ideally suited for our Mechanical Control Products.

HG Hydrolok

HG Series

  • Extremely lightweight – 50% weight savings over traditional hydraulic locks
  • Best-in-class ultimate load of 4,000 lbf
AL Hydrolok

AL Series

  • Aluminum impact extruded cylinder
  • Integral clevis attachment end

HL / HV Series

  • Machined aluminum cylinder
  • Machined clevis attachment end
  • Automatic fluid replenishment

Markets | Applications

airline seating


  • Main cabin seating
  • Pilot and crew seats
  • Storage bins
  • Crew rest modules
  • Elevator and door actuation
  • Transportation

  • Passenger rail
  • Charter / VIP and public buses
  • Ferries

Performance Specifications

  HG Series AL Series HL Series HV Series
Override Force 50-130 lbf*        70 lbf 70 lbf 70 lbf
Button Force 6-12 lbf* 4 lbf  4 lbf  4 lbf 
Compression Load 4,500 lbf 3,000 lbf 3,000 lbf 3,000 lbf
Tensile Load 4,000 lbf 3,000 lbf   3,000 lbf   3,000 lbf  
Proof Load 1,000 lbf 1,500 lbf 1,500 lbf 1,500 lbf
Speed to Extend 0.3-0.6 sec.* 0.4 sec. nominal 0.4 sec. nominal 0.4 sec. nominal
Nominal Weight 4-6 oz.* 9 oz. 9 oz. 9 oz.
Available Stroke 0.50-2.10 in. 0.0-1.38 in. 0.31-3.19 in.   0.0-2.50 in.
Mounting Length 3.94-8.16 in.* 6.1-9.8 in.* 4.12-12 in.* 4.12-12 in.*
Output Force Compressed† 50-170 lbf 55-160 lbf 45-330 lbf 60-320 lbf
Output Force Extended† 40-130 lbf 25-110 lbf 50-140 lbf 35-180 lbf
* Exact specifications configurable by customer. 
† Output forces vary with mounting length.

How it Works

airline seat cutaway

The cylinder-and-piston design of the Hydrolok uses an integral valve and porting system. This design gives passengers a smooth reclining motion by creating a controlled flow of hydraulic fluid from one side of the piston to the other.

All Hydroloks use Crane’s proprietary hydraulic seal technology to prevent leaks and increase the life of the system.

Hydroloks also have an auxiliary reservoir chamber that replenishes the very small amount of hydraulic fluid used with each passenger input. This assures consistent operation and long cycle life for operators.