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Frequently Asked Questions
What is a lock valve assembly?
A block combining the holding elements - checks, counterbalance cartridges and sometimes a relief - into a single component that bolts directly to the cylinder port face. It packages the holding function rather than introducing a new hydraulic principle. It is bought as much for the mounting it guarantees as for the valves inside it.
Why does it bolt straight to the cylinder?
Because a hose failure between valve and cylinder would release the load, and machinery safety standards for lifting equipment are written around that failure. Bolting to the port face satisfies the requirement by construction, rather than depending on someone plumbing it correctly.
Where are they typically found?
Access platforms, telehandlers, tail lifts, tipping bodies and outrigger legs - equipment where a suspended or raised load must not fall and where the holding arrangement forms part of the machine's approval. They are standard rather than optional on that class of equipment.
What advantages does the single block give?
Fewer joints to leak, no exposed interconnecting pipework to be damaged in service, and one item to specify, order and certify. On equipment subject to type approval or periodic inspection, having the holding function as a single identifiable component simplifies the paperwork considerably.
How do I select one?
By the cylinder port pattern and by which functions the block must contain. Both must match - a block that is hydraulically correct but wrong on the port face cannot be fitted, and one omitting a function the circuit relies on removes that function without anything obviously changing.
Will an inspector look at it?
On statutorily inspected equipment, generally yes - the holding arrangement is central to the safety case for a raised load, so its presence, condition, setting and mounting are all things an inspector may check directly. Records of settings are worth keeping for that reason.
Can I replace one with separate valves?
Only if the replacement still mounts on the cylinder and provides every function the original did, and on approved equipment the change may invalidate the approval. Substituting a cylinder-mounted block with remotely plumbed valves reintroduces exactly the failure mode the block exists to eliminate.