Since you have given out the machinery on hire, you are the lessor. Your customer will be the Lessee.
Firstly, I am going to assume that by saying HIRE, you were not refering to HIRE PURCHASE (Ownership gets transferred if its HP); ie., the lessee (your customer) does not have a right to purchase the machinery at end of lease period.
TAXATION ASPECT:
Now, coming to the Income Tax provisions, A lessee is not entitled claim depreciation thereon as he does not own the plant.
I. If your business is leasing: The lessor can, however, claim depreciation on the assets leased out by him if he is engaged in the business of leasing out the assets. Lease income will be taxed under PGBP head of income.
II. If your business is not leasing: Section 57 of the Income Tax act 1961, provides that if the lessor (Your entity) is not in the business of leasing, then such lease income is taxable as "Income from Other Sources" and depreciation computed as per section 32 of said Act shall be allowed.
ACCOUNTING ASPECT:
If its not a HIRE PURCHASE transaction, then you can account the same as an asset in your books of accounts and claim the depreciation accordingly. You may also refer to AS-19 only IF the same is applicable to your entity. Check applicability.
PS. The whole procedure is different if you were referring to a HIRE PURCHASE txn.
Hope this clarifies the issue.